1155. _Why, if we break the stem of a hyacinth, do we see a glutinous
fluid exude?_
Because, by breaking the stem, we rupture the vessels of the plant, and
cause the nutritive fluid to escape. The sap of the plant is _analogous
to the blood of man_, and the vessels, to the arteries and veins of the
animal body.
1156. _Why, if we split the petal of a tulip, do we see cells
containing matter of various colours?_
Because, by splitting the petal of the flower, we disclose the anatomy
of its structure, and bring to view those cells, or organs, of the
vegetable body, by which _the different colouring matters are secreted_.
1157. _Why, if we break a pea-shell across, do we discover a
transparent membrane which may be removed from the green cells
underneath?_
Because we separate from the cellular, or fleshy part of the shell, the
membrane, _which forms the epidermis_, and answers to the skin of the
animal body.
1158. _Why, if we cut through a cabbage stump, do we find an outer coat
of woody fibre, and an inner substance of cellular matter?_
Because the woody fibre _forms a kind of skeleton_, which supports
the internal stricture of the plant, and gives form and character to
its organisation. The woody fibre of plants is analogous to the bony
structure of animal bodies.
1159. _Why, if we cut across the stem of a plant do we see numerous
tubes arranged in parallel lines?_
Because we thereby bring to view _the vessels formed by the membranes
and fibres_ of the vegetable body, for the transmission of the fluids,
by which the structure is sustained.
[Verse: "It was planted in a good soil by great waters, that it
might bring forth branches, and that it might bear fruit, that it might
be a goodly vine."--EZEKIEL XVII.]
Skeleton leaves, and seed vessels of plants, form exceedingly
interesting objects, and serve to illustrate the wonderful
structure of plants. With patience and care, they may be produced
by any person, and will afford an interesting occupation. The
leaves should be gathered when they are in perfection--that is,
when some of the earliest leaves begin to fall from the trees.
Select perfect leaves, taking care that they are not broken, or
injured by insects. Lay them in pans of _rain water_, and expose
them to the air to undergo decomposition. Renew the water from
time to time, taking care not to damage the leaves. They need
not be examined more than once a week, and then only to see that
the water is sufficient to cover them. Give them sufficient time
for their soft parts to become decomposed, then take them out,
and laying them on a white plate with a little water, wash away
carefully, with a camel-hair pencil, the green matter that clings
to the fibres. The chief requirement is _patience_ on the part
of the operator, to allow the leaves and seed vessels sufficient
time to decompose. Some leaves will take a few weeks, and others
a few months, but a large panful may be put to decompose at the
same time, and there will always be some ready for the process
of cleansing. When they are thoroughly cleaned, they should be
bleached, by steeping for a short time in a weak solution of
chloride of lime. They should then be dried, and either pressed
flat, or arranged in bouquets for preservation under glass shades.
The result will amply reward the perseverance of the operator.
1160. _Why are clayey soils unfavourable to vegetation?_
Because the soil is _too close and adhesive_ to allow of the free
passage of air or water to the roots of the plants; it also obstructs
the expansion of the fibres of the roots.
1161. _Why are sandy soils unfavourable to vegetation?_
Because they consist of particles that have _too little adhesion to
each other_; they do not retain sufficient moisture for the nourishment
of the plants; and they allow too much solar heat to pass to the roots.
1162. _Why are chalk soils unfavourable to vegetation?_
Because they do not absorb the solar rays, _and are therefore cold to
the roots of plants_.
1163. _Why are mixed soils favourable to vegetation?_
Because they contain the _elements of nutrition_ essential to the
development of the vegetables, and the plants absorb from them those
constituents which are necessary to their growth.
1164. _Why do farmers sow different crops in rotation?_
Because every plant takes something from the soil, and gives something
back; but all kinds of plants do not absorb nor restore the elements in
the same proportions. Therefore a succession of crops of one kind would
soon impoverish the soil; but a succession of crops of different kinds
will compensate the soil, in some degree, for the nourishment withdrawn.
[Verse: "He watereth the hills from his chambers; the earth is
satisfied with the fruit of thy works."--PSALM CIV.]
1165. _Why do farmers manure their lands?_
Because, as soils vary, and crops impoverish the soils, the farmer
employs manure _to restore fertility_, and to _adapt the soils to the
wants of the plants_ he desires to cultivate.
It is remarkable that Nature herself points out to man the
necessity for changing the succession of vegetable growths.
When plants have exhausted the soil upon which they grow, they
will push their roots far in search of sustenance, and in time
migrate to a new soil, while other plants will spring up and
thrive upon the area vacated. When a forest in North America is
destroyed by fire, the trees that grow afterwards are unlike
those that the fire consumed, and evidently arise from seeds that
have long lain buried in the earth, waiting the time when the
ascendancy of the reigning order of plants should cease.
1166. _Why are grasses so widely diffused throughout nature?_
Because they form the _food_ of a very large portion of the animal
kingdom. They have therefore been abundantly provided. No spot of
earth is allowed to remain idle long. When the foot of man ceases to
tread down the path, grass immediately begins to appear; and by its
universality and the hardihood of its nature, it clothes the earth as
with a carpet.
Many grasses, whose leaves are so dry and withered that the
plants appear dead, revive and renew their existence in the
spring by pushing forth new leaves from the bosom of the former
ones.--_Withering's Botany._
Grasses are Nature's care. With these she clothes the earth;
with these she sustains its inhabitants. Cattle feed upon their
leaves; birds upon their smaller seeds; men upon the larger;
for, few readers need be told that the plants which produce our
bread-corn, belong to this class. In those tribes which are
more generally considered as grasses, their extraordinary means
and powers of preservation and increase, their hardiness, their
almost unconquerable disposition to spread, their faculties of
reviviscence, coincide with the intention of nature concerning
them. They thrive under a treatment by which other plants are
destroyed. The more their leaves are consumed, the more their
roots increase. The more they are trampled upon, the thicker they
grow. Many of the seemingly dry and dead leaves of grasses revive,
and renew their verdure in the spring. In lofty mountains, where
the summer heats are not sufficient to ripen the seeds, grasses
abound which are viviparous, and consequently able to propagate
themselves without seed. It is an observation, likewise, which
has often been made, that herbivorous animals attach themselves
to the leaves of grasses; and, if at liberty in their pastures to
range and choose, leave untouched the straws which support the
flowers.--_Paley._
[Verse: "For the earth bringeth forth fruit of herself; first the
blade, then the ear, after that the full ear in the corn."--MARK V.]