8 Practical Plant Biology. 



should show the outline of the cell, the thickness of its vertical walls, the 

 limits of the protoplasm and vacuoles, the nucleus and some granules. 



Replace the low power in position ar.d take the slide from the stage. 



Draw off some of the water between the cover-glass and slide by means 

 of a piece of blotting-paper, and add a drop of liquor iodi (a solution of iodine 

 in a watery solution of potassium iodide) at the opposite side of the cover- 

 glass. 



Note how the iodine passes through the cell- wall and stains the proto- 

 plasm, especially the nucleus. 



Before leaving your microscope return the low power to position under 

 the body and remove the preparation. 



Never remove a preparation, or place it on the stage while the high power 

 is in position. Leave the diaphragm open and the plane mirror facing up- 

 wards. See that all parts of the microscope are clean and dry. 



