68 The soil cmd the pla/iit 



and place in Avater. Notice that the water at once 

 begins to rise in both tubes and will go on for a long 

 time, always passing from the wet to the dry places. 

 It rises higher in the soil than it does in the sand. 

 Enough water may pass up the tube in this way to 

 supply the needs of a growing plant. Fill a glass 

 lamp chimney with dry soil, packing it down tightly, 

 put into water and then sow with wheat. The plants 

 grow very well. A longer tube may be made from 

 two chimneys fastened together by means of a tin 

 collar stuck on with Canada balsam or sealing wax 

 (Fig. 31). Our plants grew well in this also, but on a 

 sandier soil, where the water could not rise so high, it 

 might happen that they would not. 



Thus we shall expect great differences in the mois- 

 ture of various soils. In some districts there is much 

 more rain than in others, and therefore the soils get a 

 larger supply of water. Sandy soils allow water to run 

 through while a loam holds it like a sponge, in a loam 

 also the water readily moves from wet to dry places. 

 Further, water runs down hills and collects in low-lying 

 hollows or valleys ; here, therefore, the soil is moister 

 than it is somewhat higher up. What will be the effect 

 of these moisture differences on plants ? 



You must find out in two ways. Visit a soil that 

 you know is dry — a sandy, gravelly or chalky soil in a 

 high situation — ^and look carefully at the plants there, 

 then go to some moister, lower ground and see what the 

 plants show. You cannot be quite certain, however, 

 that anything you see is simply due to water supply, 

 because there may be other differences in the soil as 

 well. So you must try the second method, and that is 

 to find out by experiments what is the effect of varying 



