MICROSCOPIC TECHNIQUE. 27 



(6) Stain with alcoholic eosin about five minutes. 

 (?') Apply ninety-five per cent alcohol to remove excess of stain 

 and dehydrate. 



(8) Clear up with creosote. 



(9) Eemove excess of creosote and mount with balsam. 



(10) Center cover-glass and label. 



(11) Lay aside in horizontal position until balsam hardens. 



Staining Unicellular Organisms. 



It is often desirable to examine material without staining. This 

 is accomplished by placing upon the glass slip a drop of the ma- 

 terial to be examined and applying cover-glass. A hair placed un- 

 der the cover-glass will prevent the object from being crushed and 

 allow of free motion in the case of living organisms. Should it 

 be desired to stain such preparations, two methods may be pursued, 

 irrigation and cover-glass staining. 



No. 9. IRRIGATION AND STAINING MICRO-ORGANISMS. 



(1) Place upon the slide a drop of material to be studied. 



(2) Apply cover-glass. 



(3) At the edge of the cover-glass, by means of a pipette, place 

 a drop or two of the reagent or stain. 



(4) By means of a triangular piece of blotting paper applied at 

 the opposite edge of the cover-glass, absorb the moisture from the 

 preparation, thus drawing under the stain. 



No. 10. COVER-GLASS PREPARATIONS. 



(1) Make a thin spread of the substance to be examined upon a 

 sterilized cover-glass. 



(2) Using a Cornet forceps, dry the preparation by holding it 

 between the fingers above a flame. 



(3) When dry pass the cover-glass three times through a flame, 

 keeping the preparation up. 



(4) Apply stain. 



(5) Wash in distilled water by dipping the cover-glass in the 

 water two or three times. 



(6) Examine as a water mount or, if desired, dry and mount 

 in balsam. 



