OOTS REACH FROM ROW TO ROW]

A deep soil is much better than a shallow soil, as its depth makes it
just so much easier for the roots to seek deep food. Fig. 21 illustrates
well how far down into the soil the alfalfa roots go.

[Illustration: FIG. 21 ALFALFA ROOT]

=EXERCISE=

Dig up the roots of several cultivated plants and weeds and compare
them. Do you find some that are fine or fibrous? some fleshy like
the carrot? The dandelion is a good example of a tap-root.
Tap-roots are deep feeders. Examine very carefully the roots of a
medium-sized corn plant. Sift the dirt away gently so as to loosen
as few roots as possible. How do the roots compare in area with the
part above the ground? Try to trace a single root of the corn plant
from the stalk to its very tip. How long are the roots of mature
plants? Are they deep or shallow feeders? Germinate some oats or
beans in a glass-sided box, as suggested, and observe the
root-hairs.

SECTION IX. HOW THE PLANT FEEDS FROM THE SOIL

Plants receive their nourishment from two sources--from the air and from
the soil. The soil food, or mineral food, dissolved in water, must reach
the plant through the root-hairs with which all plants are provided in
great numbers. Each of these hairs may be compared to a finger reaching
among the particles of earth for food and water. If we examine the
root-hairs ever so closely, we find no holes, or openings, in them. It
is evident, then, that no solid particles can enter the root-hairs, but
that all food must pass into the root in solution.

An experiment just here will help us to understand how a root feeds.

[Illustration: FIG. 22. EXPERIMENT TO SHOW HOW ROOTS TAKE UP FOOD]

=EXPERIMENT=

Secure a narrow glass tube like the one in Fig. 22. If you cannot
get a tube, a narrow, straight lamp-chimney will, with a little
care, do nearly as well. From a bladder made soft by soaking, cut a
piece large enough to cover the end of the tube or chimney and to
hang over a little all around. Make the piece of bladder secure to
the end of the tube by wrapping tightly with a waxed thread, as at
B. Partly fill the tube with molasses (or it may be easier in case
you use a narrow tube to fill it before attaching the bladder). Put
the tube into a jar or bottle of water so placed that the level of
the molasses inside and the water outside