32 
THE STORY OR THE OAK TREE 
trees too, but it is a very faint breathing, best observed 
at night when the sun-drinking chlorophyll is not work¬ 
ing. 
You know now why your mother sets her pretty potted 
plants in the window; she wants to give the chlorophyll 
or leaf-green a chance to catch the sunlight. When it is 
dark there is just as much plant-food in the air and in the 
water as when the sun shines, but the chlorophyll needs 
the heat of the sun’s rays to help prepare the air-food and 
water-food into starches and sugars which the tree can 
digest. It is the work done by the chlorophyll which 
makes it possible for us to eat plants and vegetables; we 
cannot digest air or sunlight, but we can digest them 
after the chlorophyll has finished working upon them. 
You see what sincere thanks we owe to the chloro¬ 
phyll, for from the simple starches, sugars and other 
foods prepared in the leaf kitchen come all other foods 
whatever, for animal as well as for plant. It is to the 
leaf that we must turn to discover the elements upon 
which we feed and grow; and from which we are in the 
last testing composed. 
That the leaves may catch this life-giving sunlight the 
forest oak grows tall and straight; its trunk bears no 
branches lower down where they would be overshadowed 
by other trees. Have you not seen plant leaves struggling 
out of the shadow? The ivy spreads itself upon the 
