THE ACORN, THE ROOT AND THE SEEDLING OAK 13 
What is it, do you suppose, that makes the root grow 
down and the stem grow up? People have been so 
curious to find out the reason for this that they have 
made experiments to try to fool the root. They have 
twisted the acorn round so the stem would grow down 
and the root up, but every time the wise root and stem 
have righted themselves and grown the way they knew 
was best for them. The only attraction that can bring 
the root upward is water. Roots are such thirsty things 
that when the soil is very dry and water is above, they 
will follow the moisture. 
Down there in the moist darkness that it loves the tiny 
root begins to grow. It feels its way straight down into 
the earth, for this first shoot is the central root of the 
tree, the tap root, and the tap root always grows straight 
down. The end of this root is so sensitive that men have 
called it the brain of the tree. It grows against some¬ 
thing rough, is slightly wounded, and turns away from 
the thing that has scratched it. There is a great scientist 
named Mr. Arthur Thomson who understands the trees 
so well that he can tell you better than I can just how the 
root moves. 
“It moves gently,” he says, “against grains of soil, and 
the touch causes it to move gently to and fro; it feels its 
way through the cracks of the soil. It comes to a dry 
region and bends to the moister side.” 
