X 
LEAVES ARE SUGAR FACTORIES 
with the oxygen of the air and makes carbon dioxide. 
Thus, there is always carbon dioxide in the air. To be 
sure, it is there in very small quantities — one part to 
three thousand of other elements. 
The leaf is so made that it can strain this carbon diox¬ 
ide out of the air. Having got it, the leaf still has an¬ 
other difficult thing to do. The carbon dioxide must be 
broken up. This is a hard task for the chemist working 
in his laboratory, but the leaf does it quite easily. 
The substance in the leaf that makes it green has much 
to do with this. This green breaks up the sun’s rays and 
applies some of the energy that is in them to tearing the 
carbon and the oxygen of the carbon dioxide apart. 
When it has done this, it unites the carbon with hydro¬ 
gen and oxygen from the water that it has already brought 
up from the roots, and the result is sugar. It has some 
oxygen left over, which it puts back into the air, thereby 
making the air better for animals to breathe. But from 
the sugar that it gets, it makes most of the food which 
the plant needs for growth. 
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