494 THE RESPIRATORY SYSTEM. 



Delafield describes such an mtra-alveolar formation of connective tis- 

 sue leading to fibrous induration of lobes of the lung and occurring as an 

 independent lesion apart from the exudative form of lobar pneumonia. 



CONCURRENT INFECTION AND SUPPURATIVE INFLAMMATION OF THE 

 LUNG FOLLOWING LOBAR PNEUMONIA. 



Although as stated above Micrococcus lanceolatus usually occurs alone 

 in typical lobar pneumonia, it may be accompanied by the Streptococcus 

 and Staphylococcus pyogenes and occasionally by other micro-organisms. 

 The exact significance of these mixed or concurrent infectious in lobar 

 pneumonia is not always clear. But instead of the usual resolution there 

 may be gangrene ; or suppuration of the interstitial lung tissue with the 

 formation of abscess may occur. In such cases Streptococcus pyogeues 

 and Staphylococcus pyogeues aureus or .putrefactive bacteria may be 

 present with the pueuniococcus in the exudate. 



Suppurative inflammation of the interstitial tissue of the lungs may 

 involve not only the larger fibrous-tissue bands but the walls of the air 

 vesicles and other air spaces. It is often called " purulent infiltration." 

 From the cut surface of the lungs in resolving lobar pneumonia, a gru- 

 rnous fluid resembling pus often exudes, and this is sometimes mistaken 

 for a mark of interstitial suppuration of the lung. 



Suppurative inflammation of the interstitial tissue of the lung may 

 occur without association with lobar pneumonia. 



LOBULAR PNEUMONIA AND BRONCHO-PNEUMONIA. 



In distinction from that common form of pulmonary inflammation 

 induced by the Micrococcus lauceolatus, which as we have seen is usu- 

 ally lobar in character, there are exudative inflammations of the lungs, 

 due to many different excitants, which are " patchy " or " lobular " in 

 extent, the consolidated areas varying in size from such as are scarcely 

 visible to those several centimetres in diameter. ' These patches of lobu- 

 lar consolidation often join and merge, so that solidification of whole 

 lobes or lungs is not uncommon. But the mottled, uneven surface and 

 color of the lungs on section, and the usual absence of the peculiar granu- 

 lation, ordinarily suffice for the distinction even to the naked eye of the 

 lobar from the coalescent lobular forms of exudative pneumonia. 



It is convenient to recognize several types of lobular exudative pneu- 

 monia, although the character of the exudate is not distinctive. 



1 The term lobular does not refer exclusively to the anatomical " lobule " of the lung, 

 since the masses or patches of consolidation often embrace several lobules or parts of 

 these. 



