XII 
PLANTS EAT SUGAR 
I SN’T IT ODD that the great oak tree standing by the 
roadside is found, upon examination, to have a sweet 
tooth — to be a very large eater of sugar! 
The leaves of the oak tree take carbon from the air, 
combine it with water from the roots, and manufacture 
sugar. This sugar is mixed with practically all the oak 
tree eats and becomes the chief item of its diet. 
Scientists have found that starch and sugar are chemi¬ 
cally very similar. It is easy to change one into the other. 
All plants, starting out with sugar, turn it into starch 
and then back into sugar to suit their purposes. Who¬ 
ever wants to can try a very simple experiment of turning 
starch into sugar. He has only to take a soda cracker, 
which is nearly all starch, and slowly chew it. He will 
notice that the starch in the cracker turns sweet in his 
mouth. It has undergone a chemical action that has 
changed it to sugar. 
The important difference between these two materials 
lies in the fact that sugar dissolves in water and starch 
does not. The plant transports its food supplies by water. 
It sends them through its system as sugar dissolved in 
sap. 
But when these foods have arrived at the point where 
they must be used as building materials, they are changed 
into the starch form. Starch, in fact, is sugar in storage 
form. If a bag of wheat, or a bushel of corn, or a sack 
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