What are the parts of the seed?
Compare these parts with the Morning-Glory, Sunflower, Bean, and Pea.
Where is the food stored?
How many cotyledons have Corn, Wheat, and Oats?
How many have Bean, Pea, Morning-Glory, and Sunflower?
Compare the veins of the leaves of each class and see what difference you
can find.
This will bring up the terms dicotyledon and monocotyledon. _Di_ means
two, _mono_ means one. This difference in the veins, netted in the first
class, parallel in the second, is characteristic of the classes. Pupils
should have specimens of leaves to classify under these two heads.
Flowering plants are divided first into these two classes, the
Dicotyledons and the Monocotyledons.
If Pine-seeds can be planted, the polycotyledonous embryo can also be
studied.
7. _Food of seedlings_.--The food of the Wheat seedling may be shown in
fine flour. [1]"The flour is to be moistened in the hand and kneaded until
it becomes a homogeneous mass. Upon this mass pour some pure water and
wash out all the white powder until nothing is left except a viscid lump
of gluten. This is the part of the crushed wheat-grains which very closely
resembles in its composition the flesh of animals. The white powder washed
away is nearly pure wheat-starch. Of course the other ingredients, such as
the mineral matter and the like, might be referred to, but the starch at
least should be shown. When the seed is placed in proper soil, or upon a
support where it can receive moisture, and can get at the air and still be
warm enough, a part of the starch changes into a sort of gum, like that on
postage stamps, and finally becomes a kind of sugar. Upon this sirup the
young seedling feeds until it has some good green leaves for work, and as
we have seen in the case of some plants it has these very early."
[Footnote 1: Concerning a Few Common Plants, page 18.]
The presence of starch can be shown by testing with a solution of iodine.
Starch is turned blue by iodine and may thus be detected in flour, in
seeds, in potatoes, etc.
After all this careful experimental work the subject may be studied in the
text-book and recited, the recitation constituting a thorough review of
the whole.
A charming description of the germination of a seed will be found in the
Reader. V. The Birth of Picciola.
_Gray's Lessons_. Sect. II, 8-14. III. _How Plants Grow_. Sect. I, 22, 23.
II.