62 Squamous Epithelium. 



HJEMIN CRYSTALS. 



These are interesting as demonstrating the presence 

 of blood, and they are very easily prepared, and can 

 be sealed up and kept as a permanent preparation. 

 Glacial acetic acid decomposes the blood pigment, and 

 forms a hydrochlorate of haematin in the presence of 

 sodium chloride. 



Place some ordinary table salt in a watch glass, and 

 hold it over a spirit lamp until it is thoroughly dried. 

 Take equal parts of any dried blood and this dried 

 salt on a slide, put on a cover glass, and with a capil- 

 lary tube run in glacial acetic acid, warm it gently over 

 a spirit-lamp until a good deal of the acid has evapo- 

 rated, and then examine under the microscope. To 

 mount this as a permanent preparation, wash out with 

 distilled water all the glacial acetic acid, and seal with 

 Hollis' glue. It is better to use some rather largish 

 masses of blood, or when the acid is being washed out 

 all the crystals will go as well, the larger masses will 

 be held by the weight of the cover glass, and their 

 margins wi]l be found covered with Hsemin crystals. 



EPITHELIUM. 



SQUAMOUS EPITHELIUM. 



With a blunt knife scrape a little saliva from the 

 back of the tongue or inside of the cheek, cover and 

 examine. Look for squamous epithelium, the so-called 

 salivary corpuscles showing Brownian movements of 

 the granules they contain, micrococci and in many 

 cases bacteria. 



