now is to make the pupils understand the meaning of
the answers they have given to these questions. In the first place, they
should go over their answers and substitute the botanical terms they have
just learned for the ones they have used.
COMPARISON OF THE PARTS OF THE SOAKED SEEDS.
_Morning-Glory_. A seed covering. Some albumen. Two cotyledons. A
caulicle.
_Sunflower_. An outer covering.[1] An inner covering. Two cotyledons. A
caulicle.[2]
[Footnote 1: The so-called seed of Sunflower is really a fruit. The outer
covering is the wall of the ovary, the inner the seed-coat. Such closed,
one-seeded fruits are called akenes.]
[Footnote 2: The plumule is sometimes visible in the embryo of the
Sunflower.]
_Bean_. A seed covering. Two cotyledons. A caulicle. A plumule.
_Pea_. The same as the Bean.
They have also learned how the first leaves in the last three differ from
those of the Morning-Glory, being considerably thicker in the Sunflower,
and very much thicker in the Bean and Pea. Why should the Morning-Glory
have this jelly that the others have not? Why do the first leaves of the
Sunflower change so much as the seedling grows? What becomes of their
substance? Why do those of the Bean shrivel and finally drop off? By this
time some bright pupil will have discovered that the baby-plant needs food
and that this is stored around it in the Morning-Glory, and in the leaves
themselves in the others. It is nourished upon this prepared food, until
it has roots and leaves and can make its own living. The food of the
Morning-Glory is called _albumen_; it does not differ from the others in
kind, but only in its manner of storage.[1]
[Footnote 1: Reader in Botany. III. Seed-Food.]
Also the questions have brought out the fact that the Bean and Pea
have the plumule ready formed in the seed, while the Morning-Glory and
Sunflower have not. Why should this be? It is because there is so much
food stored in the first two that the plumule can develop before a root is
formed, while in the others there is only nourishment sufficient to enable
the plantlet to form its roots. These must make the second leaves by their
own labor.
3. _Comparison with other Dicotyledons_.--The pupils should now have other
seeds to compare with these four. Let them arrange Flax, Four o-clock,
Horsechestnut, Almond, Nasturtium, Maple-seeds, etc., under two heads.
_Seeds with the Food stored _Seeds with the Food stored
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