14 
THR story or thr oak trkr 
Growing things, you see, are very sensitive. If a grow¬ 
ing stem be sharply struck it curves as though in pain, 
and stays curved for some time. When a root feels the 
pressure of a stone, it grows more slowly until it has 
grown around the stone. Climbing plants, however, like 
to feel something hard pressing against them; not until 
it feels the porch pillar against it does the Virginia 
Creeper begin to cling and climb in earnest. If you had 
something fastened to the top of your head which pulled 
you gently upward all the time, I doubt whether, when 
you are twenty, you would be much taller than Nature 
has already planned—but it helps growing plants to be 
pulled along. Trailing stems in a stream grow longer 
when the current is swift than when it is slow. 
Roots have two important things to do; one is to ab¬ 
sorb water, and the other is to hold up the tree. We have 
told how little, delicate hairs grow out along the root; 
it is these hairs which absorb the moisture. Every 
Autumn when the leaves die these hairs die also, because 
in winter the ground is frozen hard and the roots can 
gather no water. The tree in winter lives upon food 
stored up in summer, but the next Spring new little 
hairs begin to grow upon the roots and reach out for more 
water to feed the thirsty tree trunk. 
You know now what sensitive, exploring things roots 
are, but do you know how strong they are, and how 
