THE PLANT AND WATER 



203 



Practical Exercises 

 1. To Prove that Plants Throw off Water 



Put the same amount 

 of water into similar 

 vessels tumblers or 

 glass fruit jars. Pull 

 up any thrifty growing 

 plant and put its roots 

 into one of these vessels 

 of water. Stand both 

 vessels on a table side 

 by side. Note the dif- 

 ference in the amount 

 of water in each vessel 

 day by day. What has 

 caused the loss of water 

 in each vessel? Why 

 the difference? 



The same fact may be 



shown by placing a clean dry glass vessel over a grow- 

 ing plant. Where does the moisture come from that 

 appears on the inner surface of the glass? How can 

 you show that this does not come from the soil? 



2. Air-derived and Soil-derived Foods 

 Select a dry plant or a piece of dry wood. Weigh it 

 carefully. Now burn it and weigh the ashes. What 

 per cent of the plant burned? What per cent is ashes? 

 The ashes represent the food derived from the soil when 

 the plant was growing, and the part that burned repre- 

 sents the food derived from the air. 



