28 FIELD AND LABORATORY STUDIES OF SOILS 



orated in the hot sun and when an abundance of water 

 is suppUed to the roots. Sometimes in a drouth more 

 water is evaporated from the leaves than is being taken in 

 by the roots. If this is continued for some time the plant 

 wilts. This reminds us that the water in plants gives the 

 soft stems and leaves their stiffness. All the food which 

 the plant takes from the soil must first be dissolved in 

 water. It is estimated that 900 tons of water are evap- 

 orated by each acre of corn plants during the growing season. 



