EPITHELIUM. 39 



a. Isolated Cells. 



Scrape gently the inside of your cheek with the handle of a 

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

 a high power ; draiv, showing the following points : 



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



often slightly curled up at their edges. 

 ii. The niicleus 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 sp>ecimen, which has been 

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

 cleared ivith oil of cloves. Mount the specimen in halsam ; 

 cover, and examine with the high poiver. 



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 the 

 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 Kanvier'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 dofs stomach which has been stained, 

 and then cleared in oil of cloves. Mount in halsam, and examine 

 with the high power. 



i. The superficial layer consists of long narrow colum- 

 nar cells, packed together side by side, with nuclei 

 at their inner or deeper ends. 



