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the gas that is poisonous, and send back into the air 
the gas which gives life and health. 
This poisonous gas which they lay hold of, you re- 
member, is carbonic-acid gas; and carbonic-acid gas is 
what we animals send out of our bodies with every 
breath, for it is the part of the air which poisons us. 
When the schoolroom is so close that our heads ache, 
it is because so many children have been breathing out 
this gas, and we are forced to take it back into our 
bodies again. 
But when this gas is stolen by the plant, and robbed 
of its carbon, it is no longer carbonic-acid gas. Noth- 
ing of it is left but the oxygen which is pushed out 
through the cell walls; and this oxygen is as good to 
breathe as the other gas (carbon and oxygen mixed) 
is bad. 
So the plant finds good what we find poisonous. It 
takes in and keeps that which hurts us (the carbon), and 
sends out that which helps us (the oxygen). 
So you see that our lives depend on the lives of plants 
in two ways :— 
1. The plants give us the food we need for life. 
2. The plants take from the air the gas that poisons 
us, and give to the air the gas which we need for life 
and health. ; 
And in both cases it is Leaf Green and Sunbeam who 
are making life possible for us. 
Remember the great services of these two fairies 
when next you pass a green tree which is bathing itself 
in sunshine. 
