474 THE RESPIRATORY SYSTEM. 



THE EXCITANTS OF EMPYEMA. Streptococcus pyogenes is the most 

 frequent excitant of suppurative inflammation of the pleura. Ac- 

 cording to the statistics of Netter this organism has been found in a 

 little over forty per cent of the cases examined of all ages. The pneu- 

 mococcus has been found in over twenty-five per cent of cases examined. 

 The streptococcus and the pueumococcus are associated in a small pro- 

 portion of cases. Of less frequent occurrence are Staphylococcus pyo- 

 genes, Bacillus typhosus, 1 Bacillus coli communis, the gonococcus, the 

 pneumo-bacillus of Friedlauder, and the influenza bacillus. In empy 

 ema with fetid exudate, various forms of bacteria may be present. 

 While in the adult the streptococcus is most often found in the empye- 

 mic exudate, in young children the pneumococcus is, according to Ket- 

 ter, 2 most common. 



Chronic Pleurisy with Adhesions. This form of pleurisy may follow 

 one of the varieties of pleurisy just described, it may be associated with 

 emphysema and chronic phthisis, or it may occur by itself. 



After death the pulmonary and costal pleura are found thickened and 

 joined together by numerous adhesions. These changes may involve 

 only a part or the whole of the pleura on one or both sides of the chest. 



The thickened pleura is covered with mesothelium ; the new connec- 

 tive tissue may be very dense and may contain few or many cells. 

 Blood-vessels may be numerous and irregular in distribution or few in 

 number. 



Tuberculous Pleuritis. Tuberculosis of the pleura is usually secondary 

 to tuberculous inflammation elsewhere in the body, either in the lungs, 

 which is most common, or the bronchial lymph-nodes, peritoneum, bones, 

 etc., or it may be a part of a general miliary tuberculosis. 3 There may 

 be localized or widely disseminated miliary tubercles upon or beneath the 

 pleural surfaces, either in direct association with lesions beneath the 

 pulmonary pleura or apart from these or upon the costal pleura. The 

 tuberculous foci may be larger and more diffuse. The minute chara ters 

 of the inflammation are not essentially different from those found in 

 tuberculosis in connective tissue elsewhere, but the mesothelial cells cov- 

 ering the pleura may share largely in the early phases of the new growth. 



If the process be prolonged, much dense fibrous tissue may be formed 

 in which are miliary tubercles in various stages of coagulation necrosis 

 or larger patches of uecrotic tissue surrounded by miliary tubercles or 

 diffuse tuberculous tissue. 



With^all types of tuberculous inflammation of the pleura more or less 

 exudate may form. This may be sero-fibrinous, often with very little 

 fibrin, or, as is frequently the case, it is tinged or deeply colored with 



1 Consult for cases bibliography Oordinier and Lartigau, Am. Jour. Med. Sciences, 

 vol. cxxi., p. 43, 1901. 



2 Netter, Bouchard and Brissaud's "Traite de Medecine," t. vii., p. 445, 1901. For 

 a study of the ways of infection of the pleura see Grrober, Deutsches Arch. f. klin. Med., 

 Bd. Ixviii., p. 296, 1900, bibliography. 



3 For evidence of the frequency of primary tuberculosis of the pleura, consult 

 Hodenpyl, New York Medical Record, June 24, 1899. 



