Procedure

Take some fresh Hydrilla plants and insert their cut ends in¬side the lower end of the glass tube.

Fill the flask with distilled water and add a few ml of 0.1% KHCO3 soln.

Fill the cylindrical cup of the glass tube with dist. water and insert a graduated water-filled glass tube over the jet.

Clamp the whole set with a stand and place under bright sun¬light.

Record the release of air bubbles produced by the green plants, passing through the jet per 5 min, when the evolution of bubbles become steady.