104 



PRACTICAL MICROSCOPY. 



SECTION OF LUNG OF PIG-. (Vide Fig. 75.) 

 OBSERVE: 

 (L.) 



1. The large scalloped openings A A, transversely divided infun- 

 dibula. 



2. The divided alveoli B B, so sectioned as to cut off both bottom 

 and top, and show no epithelial lining excepting" at inner edge of 

 periphery. 



3. The alveoli C 0, divided so as to show a cup-shaped bottom or 

 top. (The minute granules are the nuclei of the lining cells.) 



4. The alveoli D D, so cut as to leave most of bottom or top, show- 

 ing an opening in the centre where the sac has been sliced off. 



FIG. 76. TRANSVERSE SECTION OF A SINGLE PULMONARY ALVEOLUS. Stained with Hsema. 



X 400. 



A. A, A. Walls of alveolus. 



B. Lumen. 



C. C, C. Capillaries variously sectioned in their tortuous course. 



D. Pavement epithelia intact. 



E. Detached pavement cell. 



F. Detached cluster of pavement cells. 

 F'. Granular lining cells. 



G. Pulmonary artery. 



