Pathogenesis 



335 



solid, airless, and approximately like liver-tissue in appear- 

 ance. The third stage is characterized by dissolution of 

 the erythrocytes and invasion of the diseased air-cells by 

 leukocytes, so that the color of the tissue changes from 

 red to gray. At the same time the coagulated exudate be- 

 gins to soften and leave the air-cells by the natural pas- 

 sages, and the stage of resolution begins. 



In more rare cases circumscribed areas of consolidation 

 occur in the lung-tissue. The inflammatory lesions of other 



Fig. 100. Lung of a child, showing the appearance of the organ in 

 the stage of red hepatizatiori of croupous pneumonia. The pneu- 

 monia has been preceded by chronic pleuritis, which accounts for the 

 thickened fibrous trabeculae extending into the tissue, and which may 

 have had something to do with the peculiarly prominent appearance 

 of the bronchioles throughout the lung. 



