288 LESSONS IN AGRICULTURE 



the plant. These are the three principal uses ol the 

 leaves to the plant. 



Leaves make our food. Plant food is manufactured 

 in the leaves in the form of starch, is changed to sugar, 

 and with other nitrogenous matter in solution, is sent 

 to the various parts of the plant, there to be changed 

 again into root, stem, leaf, or fruit. We ought surely 

 to take our hats off to the leaves, for it is they that make 

 possible all our grain, fruit, vegetable, and flower, all 

 the wood and all the food we have, in a word all things 

 useful and beautiful are made by the leaves. 



Practical Exercises 

 1. Transpiration in the Leaf 



Take a plant that is well started in a flower-pot, a 

 piece of cardboard, and two glass tumblers large enough 

 to cover the plant. Cut a slit in the cardboard and 

 draw it around the plant. Seal the slit so that no mois- 

 ture can come through it from below. Cover the plant 

 with the glass, and allow the roots to extend into the 

 water of the glass below. Moisture will collect on the 

 inner surface of the glass. Where does it come from? 

 Is all the moisture absorbed by the roots given off in this 

 way? How could you find out? Why do plants need- 

 water? 



2. Forms of Leaves 



Collect and make drawings of seven different shaped 

 leaves. 



Leaves like the locust leaf are compound. Those like 

 the oak are simple. Classify your leaves as to whether 

 they are simple or compound. 



