The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1909-02-21

growth of additional vegetation is re-
quired, the quantity of illuminating and
heating rays increases relatively much
faster than do the chemical rays. and
the decomposition of carbon dioxide for
the building of plant tissue goes on at
an increa sed pace. But in the autumn,
as plants approach maturity. and seeds
are to be formed and fruit ripened,
the Illuminating ard chemical rays are
further increased This extraordinary
and curious instance of design In ma
ture has taught the horticulturist 20
cover seeds with blue grass when he
wishes to force their development, for
by cutting off the light and heat and
transmitting only the chemical rays. he
can hasten termination. Later, he uses
yellow glass to hasten growth by a
relative increase of the luminous rays;
and still later by using red glass ne
hastens seed and fruit formation by
admitting mainly the heat rays, while
reducing the other kinds.
We have said that the plant must
breathe; that, like the animal il must
breathe oxygen, and that 1t does so
chiefly by means of the leaves, which
are its lungs. But oxygen is constant
ly absorbed by the delicate parts of
plant foliage, and even by the roots
and the seeds, but especially by the
StOlidld Vi lHc leaves ctOIndId- or
breathing pores. the small openings in
the epidermis of leaves and soft stems.
to allow the passage of air and other
gases, have two guard cells, which open
or close the gate to the stomata as the
conditions of the atmosphere may re-
quiTe. The pores are usually most nu-
merous on the under side of the leaves.
Their number to the square inch va
ries from 200 on the leaf of a mistle-
toe to 10000 on the leaf of q lilac. so
that they are very small. AS the air
enters, the oxygen passes into the leaf
cells, and unites with carbon there,
forming carbon dioxide, which is then
exhaled. in a manner resembling the
respiration of animals. A growing plant
may absorb an amount of oxygen equal
&c its bulk in "a hours.
Assimilation.
But we have also learned that car
bon dioxide is likewise 'breathed' in by
the leaves; and whenever these have
green coloring matter (chlorophylD
present and the sun is shining, the car
bon of this gas unites with watery sub
stances In the leaf and forms starch.
while the oxygen is thrown off. This
process, by means of which the plant
is chiefly built up. since plants consist
mainly of carbon, is the chef form of
plant digestion and assimilation. Dur
ing the day. when this process is more
or less active, much oxygen may be
given off; during the night, when this
process ceases. the effect of respira-
ton is TO give off small quantities of
carbon dioxide. The starch formed IN
the leaves during the daytime is
changed into sugar and is carried at
night into the roots, tubers. or stem.
OF stored I'm the sthickened leaves, for
future growth
Transportation,
A third process carried on by the
leaves is Transportation. the means by
which the plant gets rid of its surplus
water. The plant absorbs water in
much greater quantity than il needs,
IN order to secure the proper amount
Of dissolved food substance. This wa
ter evaporates from the surfaces ri
leaves and green stems. Thousands
of minute pores aid this process also;
and these stomata open in moist and
close in dry weather. TO regulate the
amount of Transportation.
Adrian B. Pembroke, Stock Broker.