MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



Thin film method : 



1. Air-dried films are stained, without fixing, for one minute 

 with five to ten drops of the stain; then double the quantity of 

 distilled water (i.e. ten to twenty drops) is added and mixed by 

 rocking the slide gently. 



2. Allow this diluted stain to act for five to ten minutes; then 

 pour off. 



3. Wash gently with distilled water; then differentiate by 

 flooding the slide with distilled water and allowing the water to 

 remain on the slide for about one half to one minute, until the 

 film appears pink to the naked eye. 



4. Pour off; blot gently and dry in air. 



Results: 



Similar to Wright's stain. 



Thick film method : 



This method should be employed in searching for blood para- 

 sites when negative results have been obtained by the thin film 

 method. 



1 . A film is prepared by spreading three to five drops of blood 

 in a circle about 15 mm. diameter over a slide; then without 

 fixation, it is allowed to dry at room temperature from twelve to 

 twenty-four hours, protected from dust. The time required for 

 drying may be very considerably shortened by placing the slide 

 in an incubator at 37° C. 



2. Remove the haemoglobin by placing the film face down- 

 wards in a dish of distilled water at room temperature. 



3. Fix in acid alcohol for five to fifteen minutes. 



4. Wash well with distilled water ; blot gently and dry in air. 



5. Stain in accordance with the method described above for 

 thin films. 



Bacterial smears, throat exudate, etc. : 



I. Unfixed, air-dried smears are stained with i ml. of the stain 

 for two minutes; then without pouring off: 



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