276 BACTERIOLOGY. 



EhrlicJis method. Cover-glass-preparations are allowed 

 to float in a watch-glass, containing a solution of gentian- 

 violet or fuchsine, added to aniline water. A saturated 

 alcoholic solution of the dye is added till precipitation 

 commences (10 ccm, aniline water, and 10 20 drops of 

 the colour solution). The cover-glasses are left in the solu- 

 tion for about half an hour ; then washed for a few seconds 

 in strong nitric acid (one part commercial nitric acid to two 

 of distilled water), and rinsed in distilled water. After- 

 stain with vesuvin or methylene-blue, rinse in water, dry 

 and preserve in Canada balsam (Plate XX., Fig. i). 



Sections and cover-glass-preparations may be stained 

 by this method, as described by Koch.* 



Saturated alcoholic solution of methyl-violet 



or fuchsine * 1 1 



Aniline water 100 



Absolute alcohol 10 



Preparations are left for twelve hours in this solution 

 (colouring of the cover-glass-preparations can be expedited 

 by warming the solution). 



Treat the preparations with (i 3) solution of nitric acid 

 a few seconds. 



Wash in alcohol (60 per cent.) for a few minutes (cover- 

 glass-preparations need only be rinsed a few times). After- 

 stain with diluted solution of vesuvin or methylene-blue 

 for a few minutes. 



Wash again in 60 per cent, alcohol, dehydrate in absolute 

 alcohol. Clear with cedar-oil, mount in Canada balsam. 



RindfleiscJis method. Prepare a solution composed of 



Saturated alcoholic solution of fuchsine 10 drops 

 Aniline water 2 drams. 



Pour it into a watch-glass, and float the cover-glass ; 



warm the watch-glass over a spirit-lamp until steam rises. 



Remove it from the flame, and set it aside for five minutes, 



* Mittheil. aus dem Gesundheitsamte, Zweiter Band, 1884, p. 10 



