Vermont phÅ“nix. [volume] (Brattleboro, Vt.) 1834-1955, 1873-09-19
Farm and Fzres1ae.
TIE FOOD OF PL.s.y'TS.

The principal purpose of the root is to alb
sorb the food of the plant from the earth.
In what does this food consist? In substan-
ces of five kinds: water, airs or gases,
vegetable extracts, salts and earths.
Every one is aware how necessary water
is to the existence of plants; without it
they droop and fade, and are again reviv-
ed by its application. The Dubious roots,
as the hyacinths and others, grow in water
only, and many small plants may be
raised from the seed in wet cotton, sponge,
and other substances of the sort, and some
flourish upon the bare rock. Indeed wa
ter is so important and produces such con-
siderable effects, that many have supposed
that it was the only food of plants and that
from only water all its parts were created.
There are some experiments which at
first sight would appear decisive on this
point, but as they are all of similar charac-
ter we will mention but one. Van Hell
mont planted a willow weighing fifty
pounds in an earthen pot filed with earth,
which had been dried in an oven. He wa
tered it With rain or distilled water only.
Al the end of five years it was weighed
gained one hundred and nineteen and
quarter pounds, while the earth had lost
only two ounces. Hence Van belmont
concluded that the willow had derived its
nourishment from water alone.
1t has been since concluded however,
that there was fallacy in the experiment.
and that water is not the only food of plants.
For in The first place, plants cultivated in
this way do finally decline and die be ore
their natural period, and secondly the vii
low might have absorbed some vegetable
extract from the surrounding soil through
the pores of the pot Besides there is a
small quantity of earth contained in all
rain water lastly, all plants contain prin-
ciple called carbon, which is not contained
in water, and cannot bo derived from it.
Water, then, though the principal is not the
only food Of plants.
They consume also the gases of which
at atmospheric air is composed. Atmospher-
ic air is not simple but n compound sub
stance composed of two principal parts,
oxygen and ntrogen-and small proper
ton of another, carbonic acid gas or fixed
air. The two last only appear to afford
nourishment to vegetables, though the for
mer, namely, nitrogen gas, seems to be nee
essary both 10 animals and vegetables in
some way that is not very well understood.
The next kind of food is vegetable extract;
all haYe,observed that the upper layer of
the earth is black mould. This mould is
composed of decayed animal and vegeta-
bio substances. Now il a quantity of this
ha cta in, a.
strained off and eyaporated, it leaves a
thick mass which is called in chemical lam
guage an extract
Plants absorb also various kinds of salts,
as common salt, saltpeter, etc. These salts
are known 20 exist in the earth, and are
probably dissolved in the water, which is
taken up by the vegetable.
Lastly, plants consume various kinds of
earths, as chalk, flint, etc. The latter in
deed exists in large proportion in some
plants, as the common reed, or cane pole,
the rattan, and Dutch bush, whose outer
skin contains agood deal of flint.
Different vegetables require different pro-
portions of these articles of food, and will
not flourish well except in situations which
supply them. Thus the willow loves Z wet
soil, and the grape dry one, etc. The ex-
perience of man has taught him to supply
the deficiency or exhaustion of soils, by
various additions which are known by the
general name of dressings or manures.
These usually contain quantity of veget-
able extract, which seems to be one of the
most important articles.
As plants also require different kinds OF
food, another agricultural art is to raise va.
rious crops in succession upon the same
spot, so that one shall obtain what the for.
mer had left. The SOIL in this way, how.
ever, is finally exhausted and requires ell
Their artificial dressing, or else to be aban
doned for a time to natures influences
from which il at length derives the maleri
ais for renewed fertility.
These various articles are absorbed from
the soil by the roots, and sometimes will
great rapidty. DR.. Hales laid bare the roo
of a pear-tree half an inch in diameter, and
eemented 1t into tube, which was filled