To find out how quickly the roots reach out into the soil, wash the soil away from some seedlings that have been growing only a few days, say, seven, ten and fifteen. (See Fig. 11.)

From our observations, then, we have learned the important lessons of deep, thorough plowing, careful shallow after-cultivation, and that fertilizers should be well mixed with the soil.

We are now ready to go back to our study of the habit of growth of roots, and can perhaps tell something of how the root does its work for the plant.

It is very easy to see how the roots hold the plant firmly in place, for they penetrate so thoroughly every part of the soil, and to such distances, that they hold with a grip that makes it impossible to remove the plant from the soil without tearing it free from the roots.

It is also on account of this very thorough reaching out through the soil that the roots are able to supply the plant with sufficient moisture and food.

We have doubtless observed that most of these roots are very slender and many very delicate.  How did they manage to reach out into the soil so far from the plant?  Or where does the root grow in length?  To answer this question I will ask you to perform the following experiment: 

=Experiment.=—­Place some kernels of corn or other large seeds on a plate between the folds of a piece of wet cloth.  Cover with a pane of glass or another plate.  Keep the cloth moist till the seeds sprout and the young plants have roots two or three inches long.  Now have at hand a plate, two pieces of glass, 4 by 6 inches, a piece of white cloth about 4 by 8 inches, a spool of dark thread, and two burnt matches, or small slivers of wood.  A shallow tin pan may be used in place of the plate.  Lay one pane of glass on the plate, letting one end rest in the bottom of the plate and the other on the opposite edge of the plate.  At one end of the piece of cloth cut two slits on opposite sides about an inch down from the end and reaching nearly to the middle.  Wet the cloth and spread it on the glass.  Take one of the sprouted seeds, lay it on the cloth, tie pieces of thread around the main root at intervals of one-quarter inch from tip to seed.  Tie carefully, so that the root will not be injured.  Place the second pane of glass over the roots, letting the edge come just below the seed, slipping in the slivers of wood to prevent the glass crushing the roots.  Wrap the two flaps of the cloth about the seed.  Pour some water in the plate and leave for development. (Fig. 12.) A day or two of waiting will show conclusively that the lengthening takes place at the tip only, or just back of the tip.  Is this fact of any value to the farmer?  Yes.  The soft tender root tips will force their way through a mellow soil with greater ease and rapidity than through a hard soil, and the more rapid the root growth the more rapid the development of the plant.  This teaches us again the lesson of deep, thorough breaking and pulverizing of the soil before the crop is planted.