214 ROOT-PRESSURE 



CAUSE OF THE ASCENT OF THE WATER UP 

 THE STEM. 



So far nothing has been said concerning the forces which 

 cause water to travel from the root -stem up to the leaves. 

 This question cannot be fully answered. There are two forces 

 which aid the process — (i.) Root-pressure pushing the water up 

 from the roots; (ii.) transpiration pulling the water to the 

 leaves. Beyond these two bare statements it is impossible to 

 go at present. 



