HUMAN LUNG. 10 5 



5. Openings, E E, which are about the same size and bear a general 

 resemblance to those of Obs. 2. (Note that their internal edges are 

 smooth and not ragged. They are terminal bronchi. No larger 

 bronchi have been included in the section.) 



HUMAN LUNG. SECTION SHOWING A SINGLE 

 ALVEOLUS. (Fig. 76.) 



OBSERVE: 



(M 



1. The outline of alveolus. (The alveoli in human lung will 

 show much distortion, as the tissue cannot be secured in perfect con- 

 dition.) 



(H.) 



2. The fibrous wall A A. 



3. The lumen B. (The bottom or top has been cut off in making 

 the section.) 



4. The tortuous capillaries CO, in the fibrous wall. * 



5. The lining epithelial cells, (a) Those remaining attached 

 to the edges of the wall D. (b) Detached cells E. (c) Groups 

 partly detached F. 



G. The divided pulmonary artery G. (A medium-sized bronchus- 

 existed in the section immediately to the left of the artery.) 



7. Portions of the capillary plexuses in other alveoli- (not shown 

 in the figure), and especially demonstrable when they may happen to 

 contain blood-corpuscles. 



