172 ATLAS OF BACTERIOLOGY. 



at each staining a fresh preparation of anthrax bacil- 

 lus should be stained at the same time and all prepa- 

 rations differentiated with alcohol for an equally long 

 time (one or two minutes). We can then judge very 

 well whether one variety of bacteria retains or gives 

 off the coloring matter. 



3. Capsule Preparation. According to Johne we 

 proceed in the following manner : 



(1) Heating the preparation with two-per-cent so- 

 lution of gentian violet until steam is given off. % 



(2) Washing with water. 



(3) Moistening with two-per-cent acetic acid for 

 six to ten seconds. 



(4) Washing with water. 



By this method a very distinct membrane around 

 the intensely colored bacterium cell can often be 

 demonstrated in varieties which are not regarded as 

 "capsular bacteria." The capsules are seen best on 

 examination in water. 



4. Staining of Flagella. The flagella, which are 

 almost always invisible when unstained, are generally 

 prepared according to Loffler's method : 



(1) Rubbing up a trace of young agar streak cul- 

 ture (not bouillon) in a very small drop of water; 

 spread out well, dry rapidly. 



(2) Heating of the preparation with mordant until 

 steam is produced (do not boil) for one-half to one 

 minute. 



(3) Washing off in a vigorous stream of water. 



(4) Washing off in alcohol in order to remove the 

 remains of the mordant adherent at the edges. 



(5) Dropping of the staining fluid (a few crystals 

 are dissolved in 10 c.c. aniline water, and then one 



