MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



Technique : 



1. Fresh, air-dried smears are fixed for five minutes in pure 

 methyl alcohol. 



2. Allow the smears to dry in air ; then add a few drops of i % 

 potassium hydroxide aqueous solution followed immediately by 

 twice the number of drops of basic fuchsin solution. 



3. Rock the slide to ensure thorough mixing of the two solu- 

 tions; then leave until the liquid becomes decolorized, which 

 should take about three minutes. 



4. Pour off excess and rinse the preparation thoroughly with 

 distilled water. 



5. Drain, and blot dry carefully but thoroughly. 



6. If it is desired to preserve the preparation it should be 

 mounted at once in Cristalite. 



Results: 



Treponema pallidum, scarlet. Background, pink. 



BREED'S STAIN 

 For staining and counting bacteria in milk 



Solution required: 



Methylene Blue . . . . . . 0-3 gm. 



95% alcohol .. .. .. 30 ml. 



Distilled water . . . . . . 100 ml. 



Phenol . . . . . . . . 2| gm. 



Shake well until dissolved. 



Technique: 



1 . Mark off i sq. cm. on a piece of white paper and superimpose 

 a slide. 



2. Place 00 1 ml. of the milk to be tested on the slide and 

 spread, by means of a needle, into a film exactly i sq. cm., as indi- 

 cated by the marking on the paper. 



3. Dry on a level surface, by heating gently. 



4. Immerse in xylol for a few minutes to remove the fat ; drain 

 well; wash with absolute alcohol; then 95% alcohol; immerse in 

 90% alcohol for a few minutes. 



350 



