FLAGELLA STAINING. 15 



alcohol and ether, and while moist passing them through 

 the flame. Cover glasses may also be cleansed by the 

 method advised by van Ermenghem, as follows: 



Boil the cover glasses for five minutes in the follow- 

 ing solution, 



Potassium bichromate . 6 grammes. 



Sulphuric acid .... 6 grammes. 

 Water 100 cc. 



From this solution wash through several dishes of 

 distilled water, and tlien place in alcohol. Before using 

 pass through the flame. 



{a) Prepare thin films from the emulsions; dry and 

 fix in the flame. 



(6) Cover the film (held in forceps) with the mordant, 

 and hold high over the flame till it steams gently for 

 one minute. (Or float the film in the warmed mordant 

 for the same period.) 



(c) Wash thoroughly in large amounts of distilled 

 water. 



(d) Pour on now some of the stain, and again heat 

 gently for one minute (or place in the warmed stain). 



(e) Wash in water, dry and mount in Canada balsam. 



Those bacteria which stain by Gram's method can 

 be treated after the stain by iodine in the usual manner. 

 Fair results are usually obtained by this method. 

 Better microscopic pictures can be secured by van 

 Ermenghem's method, but his method is longer and 

 usually requires considerable practice. 



