CH. III.] 



PAVEMENT EPITHELIUM 



23 



minutes in a 1 per cent, solution of nitrate of silver ; it is taken out, 

 washed with distilled water, and exposed in water or spirit to sun- 

 light. The silver forms a compound with the cement, which in the 



FIG. 28. From a section of the lung of a cat, stained with silver nitrate. N. Alveoli or air-cells, 

 lined with large flat, nucleated cells, with some smaller polyhedral nucleated cells. (Klein and 

 Noble Smith.) 



light is decomposed or reduced, leading to a fine deposit of silver, 

 showing as black or brown lines between the cells, and accurately 

 defining their" outlines. The preparation may then be immersed in 

 some stain like logwood to bring out the nuclei, and finally mounted 

 in the usual way. 



FIG. 29. Abdominal surface of central tendon of the diaphragm of rabbit, showing the general 

 polygonal shape of the endothelial cells ; each cell is nucleated, x 300. (Klein.) 



Fig. 28 shows the appearance presented in a preparation of lung. 

 In the alveoli or air-sacs of the lung, pavement epithelium of a typical 

 kind is found forming a lining membrane. 



