112 A MANUAL OF BACTERIOLOGY 



Capsule Staining 



Many organisms, especially in the tissues or body fluids, 

 are invested with a capsule of gelatinous matter, probably 

 derived from the membrane of the bacterial cell, and 

 differing in composition in different species. The capsule 

 may be as thick as the bacterial cell itself, and appears, 

 in the unstained state or after staining by the ordinary 

 methods, as a clear halo or zone surrounding the organism. 

 Organisms in films of albuminous matter often appear to 

 be surrounded by a clear halo, which must not be mistaken 

 for a capsule. As organisms frequently lose their capsules 

 on ordinary culture media, Moore recommends cultivating 

 in fluid serum to obtain the re- development 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 



Rinse in water and then stain for fifteen seconds in a very weak 



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



dry, and mount. 



2. McConTcey'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. Friedlander'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 



