Chap. IV.] 



ENDOTHELIUM. 



27 



are more or less polygonal, or slightly elongated. Their 

 outlines vary ; in the lining of the lymph sacs of the 

 frog they are much larger, and of very sinuous out- 

 line ; while those of the posterior surface of the cornea 



a 



s 



Pig. 19.- Omentum of Babbit, stained with Nitrate of Silver. 

 a, Ordinary flat endothelial cells ; 6, germinating cells. (Atlas.) 



are very regular, pentagonal, or hexagonal, having 

 straight outlines in the perfectly normal and well-pre- 

 served condition, but serrated and sinuous after they 

 have been prepared with various reagents and in the 

 abnormal state ; the endothelial plates lining the blood- 

 vessels and lymphatic vessels (Fig. 18) are narrow and 

 elongated, with more or less sinuous outlines. In the 

 lymphatic capillaries the endothelial plates are poly- 

 gonal, but their outline serrated. 



32. As a rule the endothelial cells are flattened, 



