108 



STUDIES OF TREES 



Their broad blades are a device to catch the sunlight 

 which is needed in the process of digesting the food of 

 the tree. The leaves are arranged on the twigs in such 



FIG. 87. Characteristic Form and Branching of Trees. 

 The trees- in the photograph are pin oaks. 



a way as to catch the most sunlight. The leaves take 

 up the carbonic acid gas from the air, decompose it under 

 the influence of light and combine it with the minerals 

 and water brought up by the roots from the soil. The re- 

 sulting chemical combinations are the sugars and starches 



