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Fig. 50.—The Grasp of a Plant on the Particles Of Earth. A grass plant pulled in a garden.
Suggestions (Chaps. VII and VIII).—25. Tests for food. Examine
a number of roots, including several fleshy roots, for the
presence of food material, making the tests used on seeds. 26.
Study of root-hairs. Carefully germinate radish, turnip, cabbage,
or other seed, so that no delicate parts of the root will be injured.
For this purpose, place a few seeds in packing-moss or in the folds
of thick cloth or of blotting paper, being careful to keep them moist
and warm. In a few days the seed has germinated, and the root
has grown an inch or two long. Notice that, except at a distance
of about a quarter of an inch behind the tip, the root is
covered with minute hairs (Fig. 44). They are actually hairs;
that is, root-hairs. Touch them and they collapse, they are so
delicate. Dip one of the plants in water, and when removed the
hairs are not to be seen. The water mats them together along
the root and they are no longer evident. Root-hairs are usually
destroyed when a plant is pulled out of the soil, be it done
ever so carefully. They cling to the minute particles of soil
(Fig. 46). The hairs show best against a dark background.
27. On some of the blotting papers, sprinkle sand; observe how
the root-hairs cling to the grains. Observe how they are flattened
when they come in contact with grains of sand. 28. Root hold of plant. The
pupil should also
study the root hold.
Let him carefully pull
up a plant. If a plant
grow alongside a
fence or other rigid
object, he may test
the root hold by securing
a string to
the plant, letting the
string hang over the
fence, and then adding
weights to the
string. Will a stake
of similar size to the
plant and extending
no deeper in the
ground have such
firm hold on the soil?
What holds the ball
of earth in Fig. 50?
29. Roots exert pressure. Place a strong bulb of hyacinth or
daffodil on firm-packed earth in a pot; cover the bulb nearly to
the top with loose earth; place in a cool cellar; after some days
