66 THE LUNGS, BY FRANZ EILHARD SCHULZE. 



edges at the points of dichomotous division of the whole series 

 of air-passages, are invested by these thin transparent plates, 

 the boundary lines of which, brought into view by the action 

 of solution of nitrate of silver, for the most part cross them 

 transversely. The granular epithelial cells are never situated 

 upon the capillaries, but constantly invest the alveolar wall 

 within their meshes; but so that the number of cells far 

 exceeds that of the meshes. They exhibit, especially in adult 

 Men, more rarely in other Mammals, the same small spheroidal, 

 black, pigment granules, that in all but children are present 

 in the alveolar walls ; more abundantly in the interstitial con- 

 nective tissue intervening between the lobules of the alveolar 



Fig. 133 B. 



Fig. 133 B. Alveolus from the lung of a Cat, filled and hardened 

 in Miiller's solution, a a, Epithelial cells with granular contents ; 

 6 6, capillaries with blood corpuscles. Magnified 300 diameters. 



parenchyma accompanying the bronchia and vessels ; especially 

 abundant in the bronchial lymphatic glands; and usually 

 grouped into rounded or stellate masses around clear nuclei. 

 More rarely they are diffusely scattered, but always confer upon 

 the lungs of adults their peculiar spotted black appearance. 



