HOW PLANTS DO THEIR WORK 291 



It will be an easy matter to show that roots seek moist- 

 ure. Remove a portion of the bottom of a chalk box. 

 Tack a piece of wire screening over the hole. Now put into 

 the box about three inches of moist sand or sawdust. 

 Place directly over the screening three or four beans or 

 grains of corn. Set the box upon blocks. Keep the sand 

 moist. Lift up the box occasionally and examine from 

 beneath. Can you see the roots? Did any of them grow 

 through the wire ? Why did they turn backward ? 



This characteristic of roots to seek moisture may be 

 shown in another way. Trim a little off the side of a chalk 

 box lid so you may push it down into the box, making a 

 partition through the middle. Near the bottom of this 

 partition cut or bore a hole as large as a half dollar, and 

 tack a piece of wire screening over it. Place clean sand or 

 soil in the box, and plant beans or corn on one side. After 

 the seeds have germinated, put a very little water on the 

 side of the partition where the plants are growing; just 

 enough to keep them alive. Keep the other side well 

 moistened. After two weeks, carefully dig down and 

 examine the roots. Have you any evidence that the roots 

 seek moisture? 



If in a field the level of the free water lies near the sur- 

 face in the spring, will the young plants send their roots 

 very far down into the soil ? 



Experiment. Take two tin cans. In the bottom of 

 one punch holes for drainage. Fill each with moist soil 

 and plant corn or beans. Set them side by side. Place 

 exactly the same amount of water in each from day to day. 

 Do not water too much. After a few weeks note the effect 

 on the roots. Which have sent their roots farther down? 



