EXERCISE 47 



Problem. What is the relation of light to starch-making ? 



What to use. A growing plant ; an opaque mask (made of black paper) ; pins ; 

 pieces of cork. 



What to do. After keeping the plant in a dark closet for twenty-four hours, mask 

 a portion of the upper surface of a leaf with a piece of the opaque paper, pinning 

 through small portions of cork ; place the plant so that the masked blade receives full 

 and direct rays of sunlight for several hours. Remove the masked leaf from the plant ; 

 test for starch as described in previous exercise. 



Record. Draw diagrammatic, shaded representation of what results after test; 

 write your explanation of results. 



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