212 STRONG, CROWELL, AND TEAGUE. 



of numerous monkeys and guinea pigs, in which pneumonic 

 plague had been produced by inhalation of plague bacilli, has 

 shown that the pneumonia is primarily bronchial in origin and 

 of the lobular type,^° nevertheless, very early lobar involvement 

 was very much more frequently encountered in the human cases 

 at necropsy. 



In the lobar type, the whole lobe or a portion of it 

 showed either only early inflammatory engorgement or a 

 portion of the lobe early red, with beginning gray hepa- 

 tization. Plate X illustrates a section of the lung in the 

 stage of gray hepatization. We have not seen an entire 

 lobe in the stage of gray hepatization such as is frequently 

 observed in ordinary croupous pneumonia due to the Diplococ- 

 cus pneumonise, as the patients with primary pneumonic plague 

 evidently die before this stage is ever reached. Large areas of 

 red hepatization are also rare. However, a smaller area of 

 gray hepatization, adjoining one of red hepatization and this 

 in turn shading into an area showing only engorgement, was 

 sometimes observed. Very frequently death evidently occurred 

 before any apparent hepatization had taken place and only a 

 portion of a lobe showed engorgement. Even in these instances, 

 however, enormous numbers of plague bacilli were present in 

 the lung tissue. In but comparatively few of the cases had 

 the stage of gray hepatization been reached, and evidences 

 of resolution were not encountered. 



Rarely one lung was practically norinal in appearance. How- 

 ever, in these cases in which one lung only showed pneumonic 

 infiltration, the other usually showed congestion and oedema. 

 In other instances single lobes, or all the lobes of one lung, 

 might show early inflammatory engorgement. In some of the 

 cases both types of pneumonia were encountered. In one lung 

 the lobular areas might be observed while in the other the 

 appearance of a lobar type was present. Or in the same lung 

 a smaller area of gray or red hepatization might be encountered 

 while the remainder or some part of the lobe showed pneumonic 

 infiltration in the stage of engorgement. The differentiation 

 of the so-called lobar type of pneumonic plague from other 

 varieties of pneumonia may not be as easily accomplished as in 

 the case of the lobular type. The cut surface of the pneumonic 

 lung, however, in the stage of early gray or red hepatization, 

 usually seems less granular; the condition of the bronchi and 



'" See also IV, p. 173 of this report. * 



