Leaves, Buds, Blossoms, and Branches 73 



and bread. Note that the iodin causes the starch and 

 the foods that contain starch to turn blue. Test sugar, 

 milk, meat, and other food materials that are free from 

 starch and observe that they do not give this color when 

 iodin is applied to them. 



Pull a leaf on which the sun has been shining for sev- 

 eral hours and place it in warm alcohol. Keep it in 

 the alcohol until the green coloring matter of the leaf 

 has been removed, taking care not to set the alcohol 

 on fire. When the leaf has become colorless, apply 

 the iodin test to it. Does it contain starch? If so, 

 where did this starch come from? 



Pull a leaf at sundown and put it in the dark. The 

 next morning remove the green coloring matter from 

 this leaf and also from a leaf that has remained on the 

 tree all night. Test both leaves with iodin. Which 

 one contains starch? What became of the starch that 

 was in one of the leaves? 



Cut off leafy shoots of maple, willow, or other trees. 

 Set the lower ends of the stems in water colored with 

 red ink, and place the shoots in the sun. After a half 

 hour cut the stems across and note whether the red 

 color is in the bark, wood, or pith. What part of the 

 stem conducts the water up to the leaves? Perhaps 

 you may be interested in seeing how far the colored 

 water rises in an hour. Sometimes, when shoots are 

 cut, air bubbles are drawn into the ends of the vessels 

 and the ascent of the water is blocked. This difficulty 

 may be overcome by cutting off under water a short 

 section from the lower end of each shoot. 



