158 THE first book of botany. 
can not be done by a plant without leaves ? What, 
then, is one use of leaves ? 
The action of the root in sucking up water is 
named absorption. 
The action of leaves in giving off water is called 
TRANSPIRATION. 
The roots absorb. The leaves transpire. 
There are two more words that these experiments 
illustrate. The first of these is the word organ. An 
organ is any part of a plant or animal that does a 
particular kind of work different from that done by 
other parts. 
Is the root an organ ? What do your legs do that 
no other part of your body can do ? Are they organs ? 
Is your tongue an organ ? Are leaves organs ? 
The other word to be explained is function. Or¬ 
gans have functions. The function of an organ is 
what it does. What is the function of your eye ? 
What is the function of a bird’s wings ? What func¬ 
tion of roots have you discovered by your experiments ? 
What is one of the functions of leaves \ 
Remember that the particular work any organ 
does is its function. 
THE END® 
