30 
THE STORY OE THE OAK TREE 
and you close one eye and look through the little glass and 
listen to what he says, you will see this 
The leaf has two layers of skin which enclose and pro¬ 
tect the veins we noticed with our naked eye. The lower 
skin is pierced by thousands of openings—tiny holes— 
one hundred thousand to a space as big as two postage 
stamps. Through these openings—the man with the 
microscope would call them stomata —flows in that part 
of the air which the leaf can use. At the same time, 
water is flowing into the leaf from the branches. In 
each cell, or tiny living division of the leaf, is a magic 
fluid which turns the air and water into starches and 
sugars which the tree can digest. This magic fluid is 
what makes the leaf green, so we call it leaf-green, but 
the man with the microscope calls it chlorophyll, a word 
which he made up from two old Greek words: chloros, 
meaning “green,” and phulon, “a leaf.” 
Did anyone ever tell you that it is healthy to have 
green plants in the room? I think you have been told 
of that, and perhaps you wondered why it was so. The 
air we breathe contains two important elements; one, 
called oxygen, is good for us and enters our blood. The 
other, called carbon dioxide, is a poisonous gas to us and 
to all animals, but plants live on it. It is made up of 
carbon and oxygen. Plants’ leaves absorb the carbon, 
and through their stomata they breathe out the good 
