152 ELEMENTARY HISTOLOGY 



I. Squamous Epithelium. In this the component cells are 

 flattened parallel to the surface they cover ; if the epithelium 

 is stratified, the flattening is most marked in the superficial 

 cells. 



a. Isolated Cells. 



Scrape gently the inside of your c/ieek with the handle of a 

 scalpel, and put the scrapings on a slide ; cover, and examine 

 with a hiyh power ; draw, showing the following points : 



i. The cells are large, flattened and scale-like in shape, 

 often slightly curled up at their edges. 



ii. The nucleus is oval and granular, and lies near the 

 middle of the cell ; it may be rendered more dis- 

 tinct by acetic acid or magenta. 



b. Cells in situ ; cast skin of newt. 



Take a small piece of the prepared specimen, which has been 

 stained in haematoxylin, and then, after treatment with alcohol, 

 cleared with oil of cloves. Mount the specimen in balsam; 

 cover, and examine with the high power. 



i. The cells are flattened, and fitted together at their 

 edges, like a mosaic, to form a continuous layer. 

 Each cell has a large nucleus near its centre. 



II. Columnar Epithelium. This consists of elongated rod- 

 like cells, placed vertically to the surface on which they rest. 

 If a columnar epithelium is stratified the columnar character is 

 most marked in the superficial cells. 



a. Isolated cells: from the small intestine of the frog; 



isolated by maceration for 24 hours in Ranvier's 

 alcohol, and stained with picro-carmine. 



Mount a drop of prepared specimen in glycerine ; paint a 

 ring of cement round the cover-glass ; and examine with the high 

 power. 



i. The cells, which often remain side by side in little 

 groups, are columnar in shape, with nuclei near 

 their inner or deeper ends. 



b. Cells in situ. 



Take a prepared section of dog's stomach which has been stained^ 



