148 CAPSULE STAINING 



3. Wash. Dry. Mount in balsam. 



In the author's hands this method has given better results than the following. 



The method may be modified by treating the film first with a 1 per cent, solution 

 of acetic acid for 1 minute, then drying it and afterwards staining with carbol- 

 violet. 



Simple staining with dilute carbol-fuchsin also gives quite good results. 



B. 1. Dry and fix a film on a cover-^ 



2. Stain with a drop of the following solution for 30-60 seconds : 



Acetic violet. 



Acetic acid, - 1 gram. 



Alcoholic solution of gentian -violet, or crystal- violet, - 5 c.c. 



Distilled water, - 100 grams. 



3. Wash. Dry. Mount in balsam. 



C. Rsebiger suggests staining the dried but unfixed films in the following 

 solution, which must be filtered : 



Gentian-violet, - - 15 grams. 



Commercial formalin, - - 100 ,. 



After staining, wash, dry and mount in balsam. The bacteria are stained 

 violet and the capsules violet with a pink tint. 



D. Nicolle recommends staining with carbol-gentian-violet followed by 

 rapid decolourization in a 1 in 3 solution of acetone-alcohol. Mount and 

 examine in water. 



Hiss fixes the films in the flame, stains in a 5 per cent, aqueous solution of gentian- 

 violet or fuchsin in the warm, then washes in a 20 per cent, solution of copper 

 sulphate, dries and mounts in balsam. 



He also recommends staining in a half -saturated aqueous solution of gentian- 

 violet followed by washing in a 0*25. per cent, aqueous solution of potassium car- 

 bonate. The films should be examined in a drop of the potassium carbonate 

 solution. 



The staining of capsules in sections requires special methods which will be 

 studied later (vide Pneumococcus}. 



SECTION III. THE STAINING OF FLAGELLA. 



Flagella are the organs of locomotion of the motile bacteria and are only 

 visible in the living unstained condition in such large organisms as the sulpho- 

 bacteria (Bacterium photometricum, Beggiatoa roseopersinica, etc.). To 

 demonstrate flagella in other motile organisms complicated staining methods 

 have to be adopted. 



1. The staining of flagella in living 1 organisms. 

 Straus' method. 



1. Place a drop of a broth culture of the organism on a slide. 



2. Add a drop of carbol-fuchsin diluted with three or four parts of water 

 and mix the culture with the stain. 



3. Cover with a cover-glass and examine at once with an oil-immersion 

 lens. 



The bacilli are stained an intense red and the flagella, which will be seen 

 especially well on the living actively-motile bacilli, assume a pale pink colour 

 with deeper red points scattered along their length. 



Note. This is a very rapid method but it only succeeds with certain organisms, 



