Part 12

You know from your last lessons that leaves are the stomach of the plant. Leaves are also the plant’s lungs.

Plants must breathe. They must breathe in and out, as you do. Also the plants must get rid of the water which they do not need after they have taken the food out of it. Much of this water passes out through the leaves.

You know when you are very warm, you feel a moisture come on your skin. That was once water in your blood. It creeps out through tiny pores over all your skin.

The plant skin has such pores. The water goes off through them. When the plant breathes out this water, then more hurries up through the cells to take its place. So the sap keeps running up and down all the time.

Plants not only send out water through the pores of the leaves, but also a kind of air or gas. If they did not do that, we should soon all be dead. Can I make that plain to you?

Did you ever hear your mother say, “The air here is bad or close”? Did you ever see your teacher open a door or a window, to “air” the schoolroom? If you ask why, you will be told “So many people breathing here make the air bad.”

How does our breathing make the air bad? When our blood runs through our bodies it takes up little bits of matter that our bodies are done with. This stuff makes the blood dark and thick. But soon the blood comes around to our lungs.

Now as we breathe out, we send into the air the tiny atoms of this waste stuff. It is carbonic acid gas. As we breathe in, we take from the fresh air a gas called oxygen. That goes to our lungs, and lo! it makes the blood fresh and clean, and red once more.

So you can see, that when many people breathe in one room they will use up all the good clean air. At the same time they will load the air of the room with the gas they breathe out.

That is why the window is opened. We wish to sweep away the bad air, and let in good air.

But at this rate, as all men and other animals breathe out carbonic acid gas, why does not all the air in the world get bad? Why, when they all use oxygen, do they not use up all the oxygen that is in the world?

Just here the plants come in to help. Carbonic acid gas is bad for men, it is food to plants. Oxygen is needed by animals, but plants want to get rid of it. Animals breathe out a form of carbon and breathe in oxygen. Plants do just the other thing. They breathe out oxygen and take in carbonic acid gas.

The air, loaded with this, comes to the plant. At once all the little leaf-mouths are wide open to snatch out of the air the carbonic acid gas. And, as the plants are very honest little things, they give where they take away. They take carbon from the air, and breathe into the air a little oxygen.

Where did they get that? The air they breathe has both carbon and oxygen in it. So they keep what they want,--that is, carbon,--and send out the oxygen.

Now it is only the green part of the plant that does this fine work for us. It is the green parts, chiefly the leaves, that send out good oxygen for us to breathe. It is the green leaf that snatches from the air those gases which would hurt us.

It is the green leaf that changes the harmful form of carbon into good plant stuff, which is fit for our food. How does it do that? Let us see.

What makes a leaf green? Bobby who crushed a leaf to see, told me “a leaf was full of green paint.”

Inside the green leaves is a kind of green paste, or jelly. Now it is this “leaf-green” that does all the work. The “leaf-green” eats up carbon. The “leaf-green” turns carbon into nice safe plant material. It is “leaf-green” that sets free good oxygen for us.

“Leaf-green” is a good fairy, living in every little cell in the leaf. Leaf-green is a fairy which works only in the day-time. Leaf-green likes the sun. Leaf-green will not work in the dark, but goes to bed and goes to sleep!

In such simple lessons as these, I can tell you only a little of what is. The deep “how” and “why” of things I cannot explain. Even the very wisest men do not know all the how and the why of the “leaf-green” fairy.

I have told you these few things that you may have wonders to think of when you see green leaves. After this lesson, will you not care more for seeds and leaves than you ever did before?

LESSON VIII.

THE COLOR OF PLANTS.

Almost the first thing that you will notice about a plant is its color. The little child, before it can speak, will hold out its hands for a bright red rose, or a golden lily. I think the color is one of the most wonderful things about a plant.

Come into the field. Here you see a yellow buttercup, growing near a white daisy. Beside them is a red rose. Close by, blooms a great purple flower. All grow out of the same earth, and breathe the same air. Yet how they differ in color.

Some flowers have two or three colors upon each petal. Have you not seen the tulip with its striped blossoms, and the petunias spotted with white and red?

The flower of the cotton plant changes in color. Within a few days this flower appears in three distinct hues. The chicory blossom changes from blue to nearly white as the day grows warm.

Look at your mother’s roses. Some are white, others are red, pink, or yellow. None are ever blue.