EXERCISE 53 



Water absorbed from the soil by the roots passes through tiny tubes, or ducts, in 

 the roots and stems to the leaves, where a part is used in starch-making, while the 

 excess passes off into the air. 



Problem. Do leaves give off water ? 



What to use. Growing plant ; rubber sheet or paraffin paper ; twine ; bell jar ; 

 vaseline. 



What to do. Tie the rubber or paper over the pot of a well-watered plant ; dry the 

 inner surface of the bell jar and place over the plant, sealing down with vaseline. 

 After twenty-four hours note changes that throw light on the problem. 1 



Record. What has happened to answer the question ? 



Questions. 1. Why does it usually feel cool and damp in a forest? 



2. How do trees help prevent floods ? 



NOTE. The process of water removal through the leaves is called transpiration. 



1 The experiment may be tried with a single healthy leaf by setting up as in B. Use a cardboard to separate 

 the air chamber from the water bottle, and seal up the space around the leafstalk with paraffin or vaseline. 



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