492 



THK RKSPIRATOKY SYSTEM!. 



surface of tlie lung is now moister, less granular, and is often covered 

 with a grumous fluid. In view of the new studies on cytolysis it seems 

 probable that here as in the removal of alien and dead organic material 

 elsewhere in the body the exudate is softened and rendered capable of 



solution by an exaggeration of the 

 normal autolytic processes (see page 

 187). ' The softened exudate is 

 gradually absorbed or may be in 

 part expectorated. The involved 

 portion of lung again contains air ; 

 the epithelium of the air spaces is 

 regenerated. 



While it is customary and con- 

 venient to describe definite stages 

 of lobar inflammation of the lung 

 red and gray hepatization and res- 



FIG. ^.-EXUDATE FROM THE LUNG IN RESOLV- OllltiOU theSC In fact HOt Only 



ING LOBAR PNEUMONIA. merge gradually into each other, 



The cells show various phases of granular and fo^ often Coexist ill different parts 

 fatty degeneration with fragmentation of the nu- 



ciei and disintegration of the ceii bodies. of the lung. The process of repara- 



tion also usually occurs irregularly, 



so that a lung in resolution may show side by side in neighboring air 

 spaces well-formed cellular and fibrinous exudate, degenerated exudate, 

 and various phases of epithelial cell repair. 2 



Associated Lesions in Other Organs. 3 Fibrinous or sero-fibriuous pleu- 

 ritis, usually with slight but often with voluminous exudate, commonly 

 accompanies lobar pneumonia. Catarrhal and fibrinous bronchitis is also 

 usually associated with the pneumonic process. Pericarditis and endo- 

 carditis are not infrequent complications ; meningitis occasionally occurs. 

 The excitant of these complications is usually the pueumococcus. 4 



Chromatolysis of the ganglion cells, albuminous degeneration in the 

 kidney, liver, and heart, hyperplasia of the bronchial lymph-nodes, to- 

 gether with leucocytosis, fever, and frequent serious enfeeblement of the 

 heart action are marks of toxseniia. The bronchial Ij'mph-uodes may 

 contain, especially in the perifollicular sinuses, and often within phago- 

 cytes, red blood cells, cell detritus, and pneumococci brought from the 

 lungs ; fibrin is frequently also present. 



In lobar pneumonia in young children, in those enfeebled by acute 

 and chronic disease, and in the aged, the lungs are often less uniformly 



1 For a study of the chemistry of resolution of the exudate see Simon, Deut. Arch, 

 f. kl. Med., Bd. Ixx., 1901, p. 604. See also references to studies on autolysis, Jacoby, 

 Cbl. f. Path., Bd. xiii., 1902, p. 2. 



For a study of the histology of acute lobar pneumonia with bibliography see Pratt, 

 Contr. to Welch Anniversary Volume, 1900, p. 265, and Johns Hopkins Hospital Re- 

 ports, vol. ix. 



3 See for resume of statistics of complications, Kerr, Trans. Chicago Path. Soc., 

 May and June, 1903, p. 274. Also for an analysis of four hundred and eighty-six cases 

 McCrne, Fysche, and Ainley, Am. Med., January 23d, 1904. 



4 For a study of blood cultures in pneumonia see Rosenow, Jour, of Infectious Dis- 

 eases, vol. i., 1904, p. 280, bibliography. 



