Fig. 3.—VEGETABLE.
What makes the real, deep-down difference is this: Plants can live on mineral matters alone, on earth and water and air, and these things they can change into their own flesh and blood, their stems and sap and fruit. Animals can only live on what the plants have already turned from dead into living material. We need water—that is a mineral—and salt and air, which are minerals too, if we are to keep alive and well. But we can not live on these things alone: we should soon die if we had no food; and all really nourishing food, all that keeps our blood warm and makes us grow, has once been vegetable. Not one bird, or fish, or animal, not one single human being, could ever have lived on this earth, in the air, or in the water, if the plants had not come first, and prepared the earth for us to live in.
These are "sure enough" fairies that are forever working their wonders for us. The roots, like elves, grope down in the earth, and gather its treasures; the leaves stretch out into the air, and gather its riches, and out of what they have collected they weave the beautiful flowers and delicious fruits and golden grain.
Fig. 4.
I should like to make very clear just the way they do this: it is very wonderful and beautiful to study how they work their spells. First, the root, as we have seen before, with its little helmet, bores its way down into the earth. If it finds no water or damp earth it soon wilts and dies, but if it finds a wet place it begins to soak up moisture. Besides the water, it sucks up all the parts of the earth that are dissolved in the water. The water it must have, and it will manage to live awhile on that alone, as Dr. Tanner did, but it can not live so very long. Poor ground means ground that has little or no plant food in it.
You know, if you ever did any gardening work, that you can stick a cutting of geranium or begonia into pure sand that has no nourishment at all in it, and that if you keep it well watered the cutting will strike out roots and bear leaves. This is, in fact, the best way to start cuttings, for mould is a little apt to rot the stem, but the sand preserves it. After a while the baby plant is tired of doing nothing but sucking, and cries for some stronger food. Then you must put it into rich earth, still giving it plenty of water. The roots, like the baby's stomach, will at first be satisfied with a very milk-and-watery diet, but after a while it must have a strengthening soup.
Fig. 5.
The roots bring the plant a good deal, but the leaves are the principal feeders. You remember, perhaps, reading about the millions of little mouths the plant has all over its leaves. These mouths bring both food to nourish and air to sustain the plant. A fish keeps itself alive by sucking the water it lives in all the while through its gills. It gets out of the water whatever it needs—air and some food. The plants are like fishes; their water is the great ocean of air that lies on the surface of the earth. They draw it in through their mouths, take out of it all they need, and then breathe the rest out again.