3. Grind the resulting mass into an amorphous powder. 4. Weigh out: Amorphous powder 0.5 grammes Dissolve in Methylic alcohol (Merck's puriss, for analysis) 100 c.c. Allow time for true solution. (About three days is sufficient.) METHOD.-- 1. Prepare film, dry, but _do not fix_. 2. Flood the unfixed film with the stain, allow it to act for 3 minutes (the methylic alcohol of the stain fixes the film). 3. Pour off the stain and wash in distilled water until the film presents a pink colour. 4. Dry and mount. ~Leishman's Stain.~-- _A._ Weigh out: Methylene blue (medicinal) 1 gramme Dissolve in Sodium carbonate, 0.5 per cent. aqueous solution 100 c.c. Keep at 65° C. for 12 hours in either a hot incubator or a water-bath; then stand in dark place at room temperature (20°C.) for ten days. _B._ Weigh out: Eosin, extra B. A. 0.1 gramme Dissolve in Distilled water 100 c.c. 1. Mix the two solutions A and B in equal volumes, 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 intensify 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 (00 crystals) 1.5 grammes rub up in a mortar with Distilled water 100.0 c.c. Add Fuchsin, saturated alcoholic solution 10.0 c.c. and make up to 200 c.c. by the addition of Distilled water 90.0 c.c. Filter. Allow the stain to stand for two weeks before use; keep in a dark place or in an amber glass bottle. Owing to the unstable character of the methyl green, this stain deteriorates after about six months. METHOD.-- 1. Prepare and fix film in the usual manner. 2. Flood the cover-slip with the stain and allow it to act for five to ten minutes. 3. Wash very thoroughly in water; if necessary, direct a powerful stream of water on the film from a wash-bottle.