the glass so they can be seen. This can best be done by planting as
you fill the glass with soil. Plant peas and beans in the same way. Do
not water the soil after planting. Set aside in a warm place and wait
for the seeds to come up.

Another method of performing this experiment is to make a box having
one side glass (Fig. 46). The length and the depth of the box will
depend upon the size of the glass you use. Fill the box nearly full of
moist soil and plant seeds of corn and beans and peas at depths of
one-quarter inch, one inch, two inches, three inches, and four
inches. These seeds can best be put in as the box is being filled.
Hold each individual seed against the glass with a stick so that when
planted they may be seen through the glass. Protect the seeds and
roots from light by using a sheet of cardboard, tin or wrapping paper
or a piece of board, and set in a warm place.

Many of the seeds planted only one-quarter inch deep will not sprout
because the soil about them will probably dry out before they take
from it enough moisture to sprout. The one and two-inch deep seeds
will probably come up all right. Of the three and four-inch deep
seeds, the corn and peas will probably make their way to the surface
because they send up only a slender shoot, which can easily force its
way through the soil. The deep-planted beans will make a strong effort
but will not succeed in forcing their way to the surface because they
are not able to lift the large seed-leaves through so much soil, and
will finally give up the struggle. If any of the deeper beans do get
up, the seed-leaves will probably be broken off and the little plant
will starve and be dwarfed. This experiment teaches us that we should
plant seeds deep enough to get sufficient moisture for sprouting and
yet not so deep that the young seedlings will not be able to force
their way to the surface.

Seeds which raise their cotyledons above the soil should not be
planted as deep as those which do not. Large, strong seeds like corn,
peas, etc., which do not lift their cotyledons above the surface,
can be planted with safety at a depth of from one to four or five
inches.

[Illustration: FIG. 42.
To show how the bean plant gets up. Notice the curved hypocotyls
pulling the seed-leaves or cotyledon out of the soil.]

[Illustration: FIG. 43.
To show how the corn-plant gets out of the soil. A slender growing
point pushes straight up through the soil, leaving the kernel b