OH. III." 



EPITHELIUM. 



This classification does not include the more specialised forms 

 of epithelium found in secreting glands, or in the sense organs, 



Fig. 30. Peritoneal surface of a portion of the septum of the great lymph-sac of a frog. 

 The stomata, some of which are open, some collapsed, are well shown, x 160. 

 (Klein.) 



nor structures like hair, and enamel of tooth, which are epithelial 

 in origin. These will be considered in their proper place later on. 



Fig. 31. A portion of the great omentum of dog, which shows, amongst the flat endo 

 thelium of the surface, mall and large groups of germinating cndothelium, between 

 which are many stomata. x 300. (Klein.) 



We shall for the present be content to study those already 

 enumerated, and take them one by one. 



