Suggestions for Laboratory Work to Precede Chapter Six 



1. Collect from various plants leaves showing the autumn 

 colors. Make a record of the colors found in different kinds of 

 trees. 



2. Look for difTerent colors assumed by leaves of the same kind 

 of tree when growing in shade and in bright sunlight. 



3. Look for the red color in leaves that have been partly shaded. 

 What is the effect of the shade? 



4. Cut longitudinal sections through the stem and base of a leaf 

 that is about ready to fall, and note the abscission layer. 



5. Examine some evergreens and determine the number of 

 years they hold their leaves. Differences in color of bark will help 

 to distinguish the growths of different years. 



6. Make a chlorophyll extract by placing leaves in warm alcohol. 

 Dilute the alcohol with a little water, and add enough benzine to 

 double the volume of the solution. Then shake thoroughly, and 

 allow to stand until the benzine has separated. The benzine will 

 contain the yellow pigments, while the chlorophyll will remain in 

 the alcohol. 



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