142 POWDERED VEGETABLE DRUGS 



5. Counting slides, to be ruled or marked as directed below. 



6. Suspending media. 



(a) Two to three per cent, solutions of gum Arabic, cherry gum. 



(b) Ten to thirty per cent, solutions of glucose, sugar, syrup. 



(c) Oils, fats, vaseline, etc. 



7. Iodine solution, to be diluted as may be required. 



8. Stains. 



(a) Loeffler's Methylene Blue. Mix 30 cc. of a saturated alco- 

 holic solution of methylene blue with 100 cc. of a 0.1 per cent, aqueous 

 solution of potassium hydrate. Filter. 



(&) ZiehPs Carbol Fuchsin. Mix 10 cc. of a saturated alcoholic 

 solution of fuchsin with 5 grams of phenol crystals and add 100 cc. of 

 distilled water. Filter. This is a diffuse stain and is used in staining 

 acid fast bacteria. 



(c) Broca's Differential Stain. To 80 cc. of the above methyl- 

 ene blue stain add 10 cc. of the carbol fuchsin. Mix and let stand for 

 several days and filter. This stain is used to differentiate between 

 dead and living bacteria. In the presence of this stain dead bacteria 

 take on a red coloration while living bacteria (living at the time the 

 stain was applied) are stained blue. 



1. Preliminary Micrometric Determinations. Determine the exact 

 areas of the fields of view under the low, medium and oil immersion 

 powers. This is done by determining the diameters of the respective 

 fields by means of the stage micrometer, employing the formula, 

 radius squared times pi (3.1416) = the area. In this manner 

 determine the areas of the fields of the three magnifying powers, and 

 record these values for future reference and use in making quantitative 

 determinations. The stage micrometer is then no longer required. 



2. General Method for Making Bacterial, Yeast and Spore Counts. 

 If it is desired to determine the relative amount of bacterial, yeast or 

 mold decomposition in a drug, food, syrup, tincture, fluidextract, 

 etc., the following methods may be used. Weigh (if solid or semi- 

 solid), or measure (if sufficiently liquid to be poured), a definite amount 

 (usually 1 gram, or 1 cc.) of a well mixed average sample of the sub- 

 stance to be examined; dilute as may be required (1:5, 1:10, 1:100); 

 mix or shake well and make the counts by means of the hemacytometer. 

 This method will be found very satisfactory with all substances 

 which contain no confusing particles, as liquid substances generally, 

 syrups of all kinds, gelatines, glue, oils, fats, meats and meat products, 

 egg albumin, etc. 



A second general method should be used if the substance to be 

 examined for bacteria should contain mineral and organic particles 



