56 PRACTICAL HISTOLOGY. 



CHAPTER II. 



THE EPITHELIAL TISSUES. 



THE epithelial tissues are studied with regard both 

 to the character and form of the individual elements, 

 and the relations these bear to one another and to 

 the membranes they cover. The latter class of ob- 

 servation can only be properly made by the study 

 of sections of the various organs and parts where 

 epithelium is found, and will therefore be left until 

 the method of making these is explained. The 

 modes of isolating and studying the individual cells 

 will, however, be best described in this place. 



Preparation 1. Scaly Epithelium, Superfi- 

 cial Layers. If a little of the saliva which moistens 

 the inside of the cheek be gently scraped off with a 

 small spatula or with the finger-nail, a number of the 

 superficial cells of the thick stratified epithelium 

 which is here met with will be brought away, with 

 it. The material thus obtained is placed upon a 

 slide and a cover-glass put over. On examining the 

 preparation numerous flattened scaly epithelium 

 cells will be seen, either entirely isolated or in little 

 patches, the cells in a patch being connected together, 

 with their edges overlapping. The cells are of con- 

 siderable size, each with a nucleus near its middle, 

 small in comparison with the size of the cell ; and 

 the substance of the cell, although clear, yet contains 

 a number of scattered granules. Moreover, lines 

 may often be seen running in various directions over 

 the surface; these are for the most part due to folds 

 or creases of its substance. Some of the cells may 

 be seen edgeways, and then, being flattened, will 

 appear narrow and linear; but on touching the 



