76 AGRICULTURE ON THE PACIFIC SLOPE 



They can be opened and closed according to the needs 

 of the plant. 



When should the stomata be opened? If we put 

 leaves, into a fruit jar and close it tightly, it will not be 

 long before we see drops of water inside the jar. The 

 water comes from the leaves. 



The leaf is always giving out water to the air. When 

 water escapes from the leaf the soil food it contains is 

 left behind in the leaf. 



The more water the leaf gives off, the more soil food 

 it gets. You will see how this is if you fill a tumbler 

 half full of salt and then put in enough water to cover 

 it. After a few minutes stir it and dip up a little of 

 the clear water in a spoon. Let the spoon stand 

 awhile. Now the water escapes from the spoon and 

 goes off into the air, just as it does from the leaf. The 

 salt will be left in the spoon just as the soil food is left 

 in the leaf. We can see the salt and other soil food in 

 the leaf if we burn it. The gray ash we get after burn- 

 ing is soil food left in the leaf when the water escaped 

 from it. 



By keeping the stomata open the plant can get more 

 soil food, because then more water escapes and is 

 replaced by water from the root. 



When should the stomata be closed? On a hot day 

 or in a strong wind, more water may escape from the 

 leaves than the root can take up from the soil. What 

 happens then? We all know how the plant then wilts 



