THE) LE)AF 
31 
element, the oxygen. The animals in their turn absorb 
this oxygen and breathe out carbon dioxide for the plants. 
So that plants and animals are both satisfied. This is a 
very wise and lucky arrangement made by that careful 
housewife, Mother Nature, who gives plenty to her 
children, but sees to it that nothing is wasted. 
This tree-breathing, this sucking in of carbon and giv¬ 
ing ofif of oxygen which is just the opposite of animal 
breathing, is called transpiration. In the scheme of Na¬ 
ture this transpiration, or pushing out of oxygen, is a 
very important process. It goes on all day and all night 
—but most busily in the daylight—throughout the entire 
tree; the oxygen passes from cell to cell along the trunk 
and branches until it reaches the leaves and escapes 
through the tiny stomata in the leaf skin. If it could not 
breathe off this oxygen the tree would smother, just as 
you would smother if you could not breathe off the pois¬ 
onous carbon dioxide. You see, the tree takes in fifty 
times as much of this burning sun-power as it can use; 
if it could not get rid of what was left over, the tree’s 
temperature would rise in a few minutes high enough to 
kill it. Which is just another way of saying the tree 
would smother. 
Plant breathing is called transpiration, animal breath¬ 
ing is called respiration. You must know, however, 
that respiration, or breathing off of carbon, goes on in 
