128 A MANUAL OF BACTERIOLOGY 



mends cultivating in fluid serum to obtain re-develop- 

 ment of the capsule. In order to stain the capsule one 

 of the following methods may be adopted. 



1. Stain the preparations by just dipping in the following 

 solution : 



Carbol-fuchsin ...... 1 part 



Distilled water ...... 1 part 



Kinse in water, and then stain for fifteen seconds in a very weak 



aqueous solution of gentian violet (0-1 per cent.). Kinse in water, 



dry, and mount. 



2. MacConkey's method. The following solution is prepared : 

 Methyl green. ..... 1-5 grm. 



Dahlia ....... 0-5 grm. 



Distilled water . . . . . 100 c.c. 



When dissolved, 10 c.c. of a saturated alcoholic solution of 

 fuchsin are added, and the whole is made up to 200 c.c. with 

 distilled water. The stain should not be used for a fortnight, and 

 should be kept in a dark place. Specimens are stained for five 

 minutes or longer, then thoroughly washed in a stream of water, 

 dried, and mounted. 



3. Friedldnder's method (for tissues). Mix : 

 Concentrated alcoholic solution of gentian 



violet ...... 50 parts 



Distilled water . . . . .100 parts 



Acetic acid . . . . . .10 parts 



Stain the sections in this solution in the warm incubator for 

 twenty-four hours. Kinse well in 1 per cent, acetic acid, pass 

 through alcohol and xylol, and mount in balsam. 



Spore Staining 



When spore-bearing bacteria are stained by the ordinary 

 methods the spores are just tinted, or remain uncoloured 

 with the outlines more or less stained. This seems to be 

 due to the fact that the spores are surrounded with a 

 slightly permeable membrane which inhibits the entrance 

 of the staining agent. By employing some method which 



