Lecture III. 27 



Smear some of the yeast suspension on a clean cover-glass. Leave it to 

 dry. When perfectly dry pass the cover-glass quickly two or three times 

 through a Bunsen flame with the smeared side uppermost. Put a drop of 

 watery gentian violet on the smear and leave for five minutes. Wash off 

 the stain under a jet of water, shake off as much water as possible and rinse 

 with a few drops of spirit. Shake off the spirit and leave to dry. When 

 perfectly dry add a drop of Canada balsam to the smear and invert it on to 

 a slide. This smear-preparation should show scarcely any trace of colour 

 when complete. Under the microscope the protoplasm should appear faintly 

 tinged and a dark speck in it indicates the presence of a nuclear structure. 



