FLAGELLA STAINS IOI 



3. Welch's Method. 



1. Prepare and fix film in the usual manner. 



2. Flood the slide with acetic acid 2 per cent.; allow the acid 

 to remain in contact with the film for two minutes. This swells 

 up and fixes the capsule and enables it to take the stain. 



3. Blow off the acetic acid by the aid of a pipette. 



4. Immerse in aniline genotian violet, five to thirty seconds. 



5. Wash in water. 



6. Dry and mount. 



4. Ribbert's Method. 



Stain. 



Measure out and mix: 



Acetic acid, glacial 12.5 c.c. 



Alcohol, absolute 50.0 c.c. 



Distilled water 100.0 c.c. 



Warm to 36 C. (e. g. t in the "hot" incubator) and saturate 

 with dahlia. Filter. 



METHOD. 



1. Prepare and fix films in the usual manner. 



2. Cover the film with the stain and allow it to act for one or 

 two seconds only. 



3. Wash thoroughly in water. 



4. Dry and mount. 



To Demonstrate Flagella. 



1. Muir's Modified Pitfield. This is the best method 

 and gives the most reliable results, for not only is the 

 percentage of successful preparations higher than with 

 any other, but the bacilli and flagella retain their rela- 

 tive proportions. 



(a) Mordant. 



Tannic acid, 10 per cent, aqueous solution ... 10 c.c. 



Corrosive sublimate, saturated aqueous solution . 5 c.c. 



Alum, saturated aqueous solution 5c.c. 



Carbolic fuchsin (Ziehl) 5 c.c. 



Mix thoroughly. 



A precipitate forms which must be allowed to settle 

 for a few hours. 



Decant off the clear fluid into tubes and centrifugalise 

 thoroughly. 



