EXAMINATION OF THE RESPIRATORY ORGAi?S. 661 



Where a cavity is found in the lung, separate examinations 

 should be made of its contents, the surface of the walls, and the 

 subjacent tissue. 



In emphysema of the lungs, the investing membrane will be 

 often found full of very small holes ; the vessels elongated, and 

 the interspaces much enlarged; and the yellow elastic fibres 

 stretched to such an extent as to be deprived of their elasticity. 



In the first stage of pneumonia, the vesicular walls contain 

 here and there collections of minute granules. The epithelial 

 cells are separated from the basement membrane ; and while the 

 nuclei are unaltered, the cell- 

 contents have become a little Fia. 367. 

 more granular. The minute 

 capillaries are very much 

 congested. As the engorge- 

 ment proceeds, granules col- 

 lect in greater quantities in 

 the air-cells; while in the 

 efl'used serum maybe detect- 

 ed distinct blood-corpuscles, 

 small nucleated cells, and 

 exudation-corpuscles. These 

 changes are shown in Fig. 

 367. 



In the second or stage of 

 red hepatization, the cavity 

 of the air-vesicle is filled with 

 cells about O-OIS of a milli- 

 metre in size, of very varied shapes, and diflFering in respect to 



Fig. 368. 



FiQ. 369. 



their contents. These are mixed vpith concrete albumen, oil- 

 granules, and free fat. (Figs. 368, 369.) 



In the third stage — that of gray hepatization — large well- 

 marked cells may be seen, containing granules and oil. Most 



