Daily American organ. [volume] (Washington, D.C.) 1854-1856, 1855-01-30
Lectures at the mithsonian Institution.
REPORTED ron THE AMERICAN ORGAN


Professor Gray delivered the closing lecture Of
his course, on vegetation, on Friday night, before
a large and attentive auditory.
Ihe vegetable was viewed as an apparatus for
transforming mineral into organic matter or earth
and air into food, through agency set in opera
ton by the sun. Organic matter is produced
when the crude sap or mineral food of the plant
Is digested in the leaves or other green parts Of
plants and this Is done only while these parts are
exposed to the light of the sun. When so ex-
posed, the foliage evolves oxygen gas which, given
off into the air, is an unerring index Of the pro
duction Of organic matter. This was shown by
comparing the plants food, viz water containing
carbonic acid and nitrogen or ammonia, with its
fabric and general products l. o. by comparing
the raw material with the manufactured article ;
the difference In chemical composition between
the two being represented by the oxygen gas that
is given up to the air by growing plants.
Viewing this as respects the influence of vege-
tation on the atmosphere, 1t is seen that plants
under the sway OF the sun, and only under this
influence, purify the air we breathe In every
step Of their growth, and in the formation of all
the materials of vegetable growth, viz: in the pro-
ducton OF all farnaceous food of sugar, &C., plants
withdraw portion of carbonic acid gas from the
air, where, If Accumulated, it would become dele
teriousto animal lfe they appropriate its carbon
they give back to the air its oxygen, the element
so needful to animal life.
Now, the same operation which removes the in
furious air from the atmosphere we breathe, and
gives back in its place the lfe-supporting oxygen,
transforms the residue into farinaceous food, or
other forms of fnourishment; so that plants, then,
while they purify the air for animals at the same
time transform ataospheye--w being part Of
it--into food, for man and animals; and this they
do only under the influence ofthe sun.
This was shown to apply also to the arotiscd
vegetable products, which are the materials of the
fabric of animals so that animals, feeding upon
herbage, fruits, or seeds, have only to accumulate
and slightly modify what the plant under the solar
radiance, has withdrawn from the atmosphere,
condensed and organized
Even the earthly parts Of vegetables are drawn
into the plant from the soil by the action of the
sun on the leaves They are the source of the
earthly parts of the animal frame. Both bones and
flesh are equally furnished by the herbage, &C., on
which the animal feeds; the organic matter is
formed, and the earthly accumulated equally under
an influence OF the sun the one elaborated out of
the air above, the other drawn up from the earth
beneath.
The vast amount of matter which has been or
ganized by plants and is existing in various forms,
was then considered in present vegetation, in de-
composing vegetable matter, in mould, peat, and
coal, and in the whole extant animal kingdom.
The lecturer explained what becomes Of all this
organized material, and the changes il underpoes,
first, In the plant ITSELF after life has departed, and
then in the living vegetables then when transferred
as food to the animal.
The reversion Of the organized matter by decay,
into the original inorganic state in which the plant
took the materials, was illustrated; then the de-
which take place in the living plants:
The material In all being ever back 70 ~ .ainAra
state in the form of carbonic acid, water, and am
monia viz in the same condition that the plant took
them Combustion Of organized matter, as of
wood, &C., produces the same result. Decay, and
many processes which are carried on in the living
plant and the respiration of animals, were then
shown to be equivalent to combustion and TO evolve
Just as much heat as would be evolved by the burn
ing Of the same material and the heat given out
was shown TO have been absorbed by the foliage of
the plant, from the sum- at the time the matter be-
came organized.
Organized matter was also viewed as in a state
of unstable equilibrium, as raised by the suns
power In the plant to this state, as IL TO height,
from which il falls back, or always tends to subside
in obedience to the forces of inorganic nature, to
the state it had before and the fall may take place
gradually, by successive downward steps, or all at
once.
In the plant and in the animal, pooer is expend
ed and pork is done, as the organic matter under
goes the downward transformation. As weight
raised by some extraneous force to a certain height
Is thus endowed with apower which Is expended as
il falls and in its fall may be made to do work. 30
the sun, in the production Of organic matter in
plants, has endowed Il with forces derived from
ITSELF which may be expended in various ways, and
Of which man takes advantage.
So II Is sun-heat, evolved by vegetable matter,
by decay in our hot beds, or by fuel burned to
warm our apartments, or 10 cook our food, or to
enable a steam engine to do mechanical work In
the case Of wood, the heat came from the sun
few years ago that Of coal many ages ago. So
the light Of pine torch, or Of camphine extracted
from the pine, recently came from the sun but in
coal gas we light our hall tonight with sunshine
stored up for this purpose by vegetation which
fourished for hundreds ofages before the creation
Of man. II Is the same also both as TO the result
and the source OF the light, whether We burn can
die made Of the wax Of the baybery or wax palm,
or Of war made out of sugar by the bee, or a tai
low candle Of material made out Of herbage or
starch, by the OK or sheep; whether we burn the
oil we may directly extract from varieties Of
Indian corn, or feed the corn to pig, and burn
the lard oil. Now, the animal is constantly con-
suming these same organic matters as food and Il
as constantly giving off carbonic acid and water
into the air from his lungs. And when we find
that the temperature Of the animal is exactly pro-
portioned to the amount OF respiration, l. c., 70
the amount Of matter decomposed, and Of carbonic
acid and water exhaled from the lungs there Is no
longer room for doubt that animal heat Is also sun
heat that our bodies are warmed with portion
OF the same radiance which, derived by shorter
route, warns our dwellings through our fuel, and
which warns the earth's surface by direct cmana-
ton from the common source.
Heat and light were then viewed as a force con.
vertible into still other forms, and among them in
to mechanical power. Every act Of muscular ener-
gy decomposes portion Of the muscle, which Is
resupplied from the food by the incorporation Of
new materials. Each organic particle brings to
the muscle, Of which II is at the moment part, a
certain energy with which II Is endowed by the
sun when Il became organic. With each contrac-
ton Of the MUSCLE O.. at each cxertion of force,
portion of this material is consumed, Of heat
evolved, Of energy expended. Once expended,
the energy can no more renew itself then the
weight once fallen can raise itself to where II was
before. The materials decomposed, in the very
putting forth Of this force rejected to the min
eral world, and have to be raised again by the suns
influence on the plant, TO the organic condition,
before they can again be endowed with power
which they lost the instant ID was exerted.
The power which the horse puts forth in draw
ing his load, Is as truly derived from the oats he
feeds on as IL the power Of the locomotive from
n AT. /. 4. Al.