146 The Microscope. 



eye may at first overlook them, but with careful search, focusing the 

 meantime slightly up and down, they will soon be discovered. Note 

 the various shapes and search for the nucleus. This may more 

 easily be found in the broad, flat cells, and is situated near the cen- 

 ter. If the nucleus is not distinct, it may be brought out by the 

 addition of a drop of dilute acetic acid to the specimen. This may 

 be added without removing the cover-glass by " irrigating " the spec- 

 imen as follows: At one edge of the cover-glass place a drop of 

 the acid, then with a blotter absorb the salt solution on the side 

 opposite the acid. The solution will be withdrawn from under the 

 cover and the acid will take its place. 



If it is desired to make permanent specimens of squamous 

 epithelium, it can be done by taking a considerable quantity of 

 scrapings and shaking them in a small test-tube in the salt solution. 

 The epithelium is allowed to settle and the solution poured off and 

 replaced with an ammonia carmine stain. They should remain in 

 this for five minutes, when it is replaced with distilled water, which 

 should be changed until the carmine is washed out. Now replace 

 the water first with dilute alcohol and this with 95^ alcohol. The 

 epithelium should be allowed to remain in the stronger alcohol for 

 several hours. With a pipette transfer a little of the epithelium to 

 a slide, absorb some of the alcohol with a blotter and add a drop 

 of oil of cloves. In five or ten minutes remove the superfluous oil 

 and mount in balsam. This method is rather tedious, but gives 

 most satisfactory results. The manipulations will have cleansed 

 and separated the cells so that when stained they make beautiful 

 objects for study. 



(B.) When familiar with the appearance of squamous epithe- 

 lium they may be looked for in the urine. Allow a specimen of nor- 

 mal, morning urine to stand for several hours in a bottle or test-tube. 

 When sufficient sediment has collected transfer a little to a slide and 

 cover. No salt solution is needed, the urine, under the circum- 

 stances, acting as a " normal " fluid. The cells when discovered will 

 be found to differ slightly from those from the mouth. They are 

 larger and more granular. The nucleus is large and clear. Many 

 of the cells are broad and flat and belong to the upper layers. A 

 few are somewhat larger, wedge-shaped and come from the middle 

 .layers, whilst others much smaller, inclined to be round and with 

 very clear outlines are found in the lower layers. These cells can 

 be stained extemporaneously by adding a di'op of a solution of eosin 

 to the specimen. 



