498 



THE RESPIRATORY SYSTEM. 



mia and oedema with more or less exudate, usually epithelial in charac- 

 ter, may develop in the dependent posterior portions of the lungs hy- 

 postatic congestion and hypostatic pneumonia. 



There is a peculiar and rare form of broncho-pneumonia associated 

 with necrosis in which forms of streptothrix have been isolated which 

 are undoubtedly the excitants of the disease. 1 Actinomyces is also an 

 occasional excitant of broncho-pneumonia. 



In all these forms of lobular pneumonia oedema and atelectasis of 

 uuinvolved portions of the lung may occur. 



It is evident that in lobular pneumonia the infectious agent may reach 

 the lungs either through the air passages or through the blood or lymph 



FIG. 279. PERSISTENT-CHRONIC BROXCHO-PXECMOXIA. 



vessels, and that differences in the portals of entry as well as in the 

 nature and virulence of the excitant and the susceptibility of the indi- 

 vidual have an important bearing both upon the course of the disease 

 and the morphology of the lesion. 



THE EXCITANTS OF LOBULAR AND BRONCHO-PNEUMONIA. The 

 excitants of broncho-pneumonia and other types of lobular pneumonia 

 are most frequently Streptococcus pyogenes (Fig. 251), the pneumo- 

 coccus, Staphylococcus pyogeues, the typhoid, diphtheria, influenza, and 

 plague bacilli, the pneumobacillus of Friedlander; the streptothrix 



1 Consult Noi-ris and Larkin, Jour, of Exp. Med., vol. v., p. 155, 1900, bibliography. 

 Also further reference on page 225. 



