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 behind.]

[Illustration: FIG. 44.
To show the use of the cotyledons. These are the plants shown in
tumbler 2, Fig 42, forty-eight hours after removing the cotyledons
from plant _B._ Plant _B_, although first up, has been handicapped by
the loss of its cotyledons.]

Seeds of carrot, celery, parsley, parsnip and egg plant are weak and