FLAGELLA STAINING QI 



Flagella Staining. 



To a beginner flagella staining is difficult; there have been many 

 well known methods devised. The simpler are as effective as the 

 more complicated but do not always make as pretty preparations. 



Flagella, being processes extending from the capsule, are, like the 

 latter, hard to demonstrate. They are not stained by the common 

 bacterial stains. In general a powerful stain mixed with a strong 

 mordant must be employed. Some methods appear to be not so 

 much a staining method in the ordinary sense but either a precipi- 

 tating of the stain in the substance of the flagella or else a decom- 

 position of silver salts in the flagella substance. To stain flagella, 

 a young culture grown on agar must be employed; glycerine agar 

 must never be used. A mass of the organism is gently mixed with 

 a drop of distilled water until a uniform emulsion is made. A dozen 

 cover-slips carefully washed and cleaned by alcohol are thoroughly 

 flamed in order to remove the slightest trace of grease. The watery 

 emulsion of bacteria is then spread over the cover-slips evenly and 

 thinly. After they are dry the bacteria are fixed by holding them 

 for a minute just above the apex of the flame with the fingers. The 

 following methods may be pursued: 



Pitfield's Method Modified by Muir. 



Two solutions are necessary for this method. 



A. Mordant. 



10 percent watery solution tannic acid 10 c.c. 



Corrosive sublimate saturated water solution 5 c.c. 



Carbol-fuchsin solution 5 c.c. 



This forms a dense precipitate which must be removed by the centrifuge, 

 or sedimentation, and the clear fluid, or mordant, is stored in a bottle. It keeps 

 for two weeks. 



B. Stain. 



Saturated watery solution of alum 10 c.c. 



Saturated alcoholic solution gentian violet 2 c.c. 



This keeps but two or three days. 



