THE ROOT 23 



it behaving in the same way. When you remember 

 that each root-hair is one httle cell, and that the 

 plant — root, stem, leaves, and flowers — is built up 

 entirely of small cells, you will see the importance of 

 the experiments we have just been making. 



12. What becomes of the fluid-foods received 

 by the root ? If you melt salt in water, and then 

 leave this water in the sun, the water will disappear 

 into the air and the salt remain. In the same way, 

 most of the fluid taken in by the roots passes into the 

 air through the leaves ; but the mineral food remains 

 in the tree. Sometimes a mineral that is not good for 

 the plant finds its way in this manner into the leaves ; 

 but when the leaves fall the plant gets rid of these 

 harmful or useless minerals. 



Exercises and Out-door Work : — 



(1) The sap gets thicker as it goes up a tree, owing to the 

 escape of water by evaporation from the leaves. Show how this 

 helps to lift the water from the roots to the leaves. 



(2) Seek opportunities of seeing how deep roots go. Railway 

 cuttings and other excavations ofter chances of study. In dry 

 districts a tiny plant may have a root 20 inches long. Summer 

 annuals especially have to make haste to tap the moisture which 

 is beyond the reach of drought. Dig up carefully some summer 

 weeds, and examine the roots. 



Composition Exercise :— Tell how a plant drinks through its 

 roots, and how the fluid is lifted up to the leaves. 



Drawing Exercise :— Take up carefully a seedling. Try to get 

 all the roots snread out as they were in the earth, and make a 

 drawing. 



