THE RESPIRATORY TRACT. 719 



ing large quantities of inflammatory corpuscles and detached 

 alveolar epithelia, which exhibit features of an endogenous new 

 formation of pus-corpuscles. A third variety is the plastic inter- 

 stitial pneumonia, which is confined to the interstitial connective 

 tissue, and which leads either to cirrhosis or to hypertrophy of 

 the lungs. A fourth variety is represented by the destructive 

 purulent pneumonia, which appears either as a uniform infiltra- 

 tion of large portions of the lung-tissue, or in the shape of 

 abscesses. 



(a) Croupous Pneumonia. The most striking feature of this 

 variety is the slight change in the interstitial connective tissue 



FIG. 320. EMPHYSEMA OF THE LUNG. BLOOD-VESSELS INJECTED. 



N, N, unchanged alveoli; D, D, dilated alveoli; F, F, ruptured alveoli; V, pulmonary 

 vein. Magnified 100 diameters. 



the blood-vessels are engorged with blood; nevertheless, the 

 walls of the alveoli are only little broadened. If we consider the 

 enormous quantity of inflammatory corpuscles present in the 

 alveoli, the conclusion becomes admissible that the majority of 

 the inflammatory corpuscles are emigrated, colorless blood-cor- 

 puscles. It is not probable that either the connective-tissue 

 frame or the detached alveolar epithelia could, in so compara- 

 tively short a time, produce such quantities of exudation corpus- 



