The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million — John Stuart Mill — John Shaqi
The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million
John Stuart Mill · en
[Verse: "The heavens declare the glory of God: and the firmament
showeth his handy work. Day unto day uttereth speech, and night unto
night showeth knowledge."--PSALM XIX.]
"The power of decomposing carbonic acid is a vital function
which belongs to the leaves and bark. It has been stated, on the
authority of Leibig, that during the night the plant acts only
as a mere bundle of fibres--that it allows of the circulation of
carbonic acid and its evaporation, unchanged. In his eagerness to
support his chemical hypothesis of respiration, the able chemist
neglected to enquire if this was absolutely correct. The healthy
plant never ceases to decompose carbonic acid during one moment of
its existence; but during the night, when the excitement of light
is removed, and the plant reposes, its vital powers are at their
minimum of action, and a much less quantity is decomposed than
when a stimulating sun, by the action of its rays, is compelling
the exertion of every vital function."
In hot, swampy countries, where vegetation is very rapid, and
the soil loaded with decomposing carbonic matter, the plants
absorb more carbonic acid than they require, and they _then_
evolve carbonic acid gas from their leaves. Hence such climates
as the West Indies are injurious to _life_, though favourable to
_vegetation_.
1147. _How do plants obtain hydrogen?_
They obtain _hydrogen_ in combination with _oxygen_ in water, and with
_nitrogen_, in the form of _ammonia_, as which it exists in animal
manures.
1148. _How do plants obtain nitrogen?_
From the _atmospheric air_, and from the _soil_, in which it is
combined with other elements.
1149. _How do plants apply these elements to the formation of their own
structures?_
When those substances which form the food of plants are absorbed,
either by their leaves or their roots, they are converted, with the aid
of water, into a _nutritive sap_, which answers the same purposes in
_plants_ as _blood_ does in _animals_.
1150. _How is the nutritive sap applied to the growth and enlargement
of the plant?_
Every seed contains a small amount of nutrition, sufficient for the
sustentation of the _germ of the plant_, until those vessels are
formed, by which the nutritive elements can be absorbed and used for
the further development of the living structure.
The earth, penetrated by the sun's rays, warms the sleeping germ, and
quickens it into life. For a short time the germ lives upon the seed,
which, moistened and warmed by the soil, yields a kind of glutinous
sap, out of which the first members of the plant are formed. And
then the tender leaf, looking up to the sky, and the slender rootlet
penetrating the soil, begin to draw their sustenance from the vast
stores of nature.
[Verse: "He causeth the grass to grow for the cattle, and herb
for the service of man: that he may bring forth food out of the
earth."--PSALM CIV.]