Lesson IV. 

 EPITHELIUM. 



(a) Pavement Epithelium, Isolated Cells. 



Scrape the inside oi tlie cheek witli a clean sUde or tlie edge 

 of a knife, mount in a drop of saliva, and cover with a slip. 



Study uuder higli power, and make use of one of the 

 smaller openings in the diaphi-agm. Observe tlie large flat 

 cells with oval or rounded nuclei showing now and then a 

 few granules in the protoplasm. You will also see the sali- 

 vary' corpuscles, leucocytes which have wandered through 

 the oral epithelium. They are slightly swollen by the ini- 

 hibition of water. 



(b) Isolated Pavemient Epithelial cells Stained in 



Hsematoxylin and Eosin. 



Tease some scrapings from tlie inside of the cheek on a cover 

 glass, dry the preparation (after teasing) over the flame, stain for 

 15 minutes in Boehmer's liaematoxj'lin, wash in flowing water, 

 stain in eosin for 5 minutes, again wash in water, and dr}' the prep- 

 aration between two filter papers. INIount in balsam. 



The nuclei are stained blue, the protoplasm red. 

 Sketch a number of the epithelial cells and salivary cor- 

 puscles as seen under the high power. 



(c) Cutaneous Epithelium from a Frog's Epider- 



mis. 



If a frog is imprisoned for some time in a jar containing a 

 small quantity of water, portions of the epidermis are from time to 

 time shed, and are found floating in the water. These thin mem- 

 branes were washed, stained in Boehmer's hfematoxylin, dehy- 

 drated in alcohol, and are now in oil of cloves. To mount, place 

 the tissue on a clean slide, remove excess of oil, add a drop of 

 Canada balsam, and cover with a slip. 



