CAPSULE STAINS 99 



and allow the mixture to stand for 12 hours with 

 occasional stirring. 



2. Filter, and collect precipitate on filter paper. 



3. Wash precipitate thoroughly with distilled water, 

 and dry. 



4. Weigh out 0.15 gramme of the dried precipitate; 

 rub up in a mortar with 5 c.c. of methylic alcohol 

 (Merck's puriss, for analysis) . 



Allow undissolved powder to settle, then decant the 

 supernatant fluid to a clean 100 c.c. measuring cylinder. 



5. Add further 5 c.c. alcohol to sediment in mortar 

 and repeat the process, and so on until all the sediment 

 has been dissolved. 



6. Now make up the fluid in the measuring cylinder 

 to 100 c.c. by the addition of more methylic alcohol. 



. METHOD. 



1. Prepare film, dry, but do not fix. 



2. Flood the unfixed film with stain, allow it to act 

 30 seconds. 



3. Add double the volume of distilled water to the 

 stain on the film, and mix with glass rod or platinum 

 loop. 



4. Allow this diluted stain to act five minutes. 



5. Wash off with distilled water. 



6. Leave some water on film for thirty seconds to in- 

 tensify the colour contrasts. 



7. Dry and mount. 



METHODS OF DEMONSTRATING STRUCTURE OF 

 BACTERIA, ETC. 



To Demonstrate Capsules. 

 1. MacConkey. 



Stain. 

 Weigh out 



Dahlia - 0.5 gramme 



Methyl green (oo crystals) . 2.5 grammes 



