watch their
growth for several days. It will soon be seen that the plants on which
the seed-leaves were left increase in size much more rapidly than
those from which the seed-leaves were removed (see Figs. 43 and 44).
Sprout some corn in the seed tester. When the seedlings are two or
three inches long, get a wide-mouthed bottle or a tumbler of water and
a piece of pasteboard large enough to cover the top. Cut a slit about
an eighth of an inch wide from the margin to the centre of the
pasteboard disk. Take one of the seedlings, insert it in the slit,
with the kernel under the pasteboard so that it just touches the
water. Take another seedling of the same size, carefully remove the
kernel from it without injuring the root, and place this seedling in
the slit beside the first one (Fig. 45). Watch the growth of these two
seedlings for a few days. Repeat this with sprouted peas. In each case
it will be found that the removal of the seed-leaves or the kernel
checks the growth of the seedling. Therefore, it must be that the
seed-leaves which appear above ground, as in the case of the bean, or
the kernel of the corn which remains below the surface of the soil,
furnish the little plant with food until its roots have grown strong
enough to take sufficient food from the soil.

[Illustration: FIG. 39.
A seed-tester, consisting of two plates and a moist cloth.]

[Illustration: FIG. 40.--A SEED-TESTER.
A plaster cast with cavities in the surface for small seeds.]

[Illustration: FIG. 41.
1. Corn-kernel showing depression at _z_. 2. Section of same after
soaking. 3. Corn-kernel after germination has begun. The seed-coat _a_
has been partly removed. 4. Bean showing scar or hilum at _h_. 5. The
same, split open. 6. Bean with one cotyledon removed, after sprouting
had begun. _a_, Seed-coat; _b_, cotyledon; _c_, epicotyl; _d_,
hypocotyl; _e_, endosperm. (Drawings by M.E. Feltham.)]

CHAPTER X

SEED PLANTING

HOW DEEP SHOULD SEEDS BE PLANTED?

=Experiment.=--Plant several kernels of corn in moist soil in a glass
tumbler or jar. Put one kernel at the bottom and against the side of
the glass, place the next one a half inch or an inch higher and an
inch and a half to one side of the first seed and against the glass.
Continue this till the top of the glass is reached (Fig. 2). Leave the
last seed not more than one-fourth inch below the top of the soil. The
soil should be moist at the start and the seeds should all be against