The D elvers in Darkness 119 



phyry and thus had etched upon the polished sur- 

 face a full length portrait of itself. 



How far do a tree's roots go down into the 

 earth ? 



Of course this depends partly upon the depth 

 of soil in the place where the tree happens to grow. 

 It depends much more upon the family habits of 

 that sort of tree. 



Oaks and ashes put forth what are called " tap- 

 roots," which go far down into the earth. The 

 tap-root of an oak may be as long as its trunk. 



A tree that grows like this, sending long strong 

 roots deep down, gets its food and drink from 

 layers of soil far below the surface. 



Pines, hemlocks, and spruces get their living in 

 quite a different way. They throw their roots out 

 sidewise and gather most of their nourishment 

 from the surface earth. 



So in a wood where oaks have been growing 

 for many years, nourishment may have been taken 

 from the earth deep down till trees with long tap- 

 roots can no longer get a living there. But in the 

 same wood, there may be plenty of nourishment 

 in the surface earth — enough to feed a forest of 

 pines. 



In land where pines have lived and fed for 

 many years, the earth near the top has lost much 

 of its richness. But there are layers of soil below 

 from which nothing has been taken, and oaks, 

 with their long tap-roots, can reach down to this 



