Procedure

Take leaf and peel off a small piece of the lower and upper epidermis (adaxial & abaxial surface) and put it in water in watch glass.

Take out the peel from the water and place it on a slide and add 2-3 drops of saffranine to stain it.

Remove the excess stain with the help of a filter paper and put a drop of glycerine on the peel.

Gently place a cover slip on the peel and examine under microscope (high power).

Count the number of stomata per focus. Repeat viewing in different fields and obtain a mean value.

Find the area of the field of the microscope by measuring the diameter with the calibrated slide or a transparent ruler.

The required area is equal to πr2 (where r is the radius of the field of view and π=3.142).

The number of stomata per square millimeter can then be calculated.

Similarly, from the other side of the leaf, the stomatal count can be made.