88 . GENERAL MICROBIOLOGY 



Apparatus. Clean cover-glasses; clean slides; cover- 

 glass forceps; platinum loop and needle; Bunsen burner; 

 small pieces of filter paper; distilled water; aqueous-alco- 

 holic solution of fuchsin, methylen blue, etc.; Canada 

 balsam; microscope. 



Note. See appendix for formulae of stains. 



Method. 1. Flame a clean cover-glass, holding it by 

 one corner with cover-glass forceps. 



2. Place one loopful of distilled water in its center. 



3. Touch the growth on slant agar lightly with a ster- 

 ilized platinum needle and transfer a very little of the mate- 



FIG. 32. For use in mounting permanent cover-glass preparations. 



(Orig.) 



rial to the drop, and only sufficient to make it very slightly 

 cloudy. - 



4. Flame the needle and allow it to cool. 



5. Spread the drop over the entire cover-glass with one 

 or two strokes of a straight needle. In the case of path- 

 ogenic microorganisms use a flat loop 2 mm. in diameter, 

 and limit the spreading to the inner three-fourths of the 

 cover-glass. 



6. Allow to dry in air. 



7. Fix the preparation on the cover-glass by passing 

 the cover-glass, specimen side up, three times through the 

 flame of a Bunsen burner. The speed is measured by 

 moving the cover-glass and forceps in a circle of 1 ft. diam- 

 eter in one second. 



