We have learned that the roots grow out into the soil in search of moisture and food, which they absorb for the use of the plant.  How does the root take in moisture and food?  Many people think that there are little mouths at the tips of the roots, and that the food and moisture are taken in through them.  This is not so, for examination with the most powerful microscopes fails to discover any such mouths.  Sprout seeds of radish, turnip or cabbage, or other seeds, on dark cloth, placed in plates and kept moist.  Notice the fuzz or mass of root hairs near the ends of the tender roots of the seedlings (Fig. 13).  Plant similar seed in sand or soil, and when they have started to grow pull them up and notice how difficult it is to remove all of the sand or dirt from the roots.  This is because the delicate root hairs cling so closely to the soil grains.  The root hairs are absorbing moisture laden with plant food from the surface of the soil particles.  The root hairs are found only near the root tips.  As the root grows older, its surface becomes tougher and harder, and the hairs die, while new ones appear on the new growth just back of the root tips, which are constantly reaching out after moisture and food.  The moisture gets into the root hairs by a process called osmose.  The following interesting experiment will give you an idea of this process or force of osmose.

[Illustration:  Fig. 10.  A plow stopped in the furrow, to show what it does to the roots of plants when used for after-cultivation.  Notice the point of the plow under the roots.]

[Illustration:  Fig. 11.  A corn-plant ten days after planting the seed.  To show how quickly the roots reach out into the soil.  Some of the roots were over 18 inches long.]

=Experiment.=—­Procure a wide-mouthed bottle, an egg, a glass tube about three inches long and a quarter-inch in diameter, a candle, and a piece of wire a little longer than the tube.  Remove a part of the shell from the large end of the egg without breaking the skin beneath.  This is easily done by gently tapping the shell with the handle of a pocket-knife until it is full of small cracks, and then, with the blade of the knife, picking off the small pieces.  In this way remove the shell from the space about the size of a nickel.  Remove the shell from the small end of the egg over a space about as large as the end of the glass tube.  Next, from the lower end of the candle cut a piece about one-half inch long.  Bore a hole in this just the size of the glass tube.  Now soften one end of the piece of candle with the hole in it and stick it on to the small end of the egg so that the hole in the candle comes over the hole in the egg.  Heat the wire, and with it solder the piece of candle more firmly to the egg, making a water-tight joint.  Place the glass tube in the hole in the piece of candle, pushing it down till it touches the egg.  Then, with the heated wire, solder the tube firmly in place.