244 
THE CULTIVATOH. 
July, 
are accounted for on the supposition that plants draw 
their nourishment both from the soil on which they stand, 
and the atmosphere that surrounds them; so that in their 
decay, they increase the fertility of the soil, by carrying 
jack, not only those elements that were drawn from it, 
hut also those that were extracted from the surrounding 
medium. These facts can be explained in no other way, 
except by the theory of shade, which is too visionary a 
conjecture to merit even a notice. 
There are multitudes of proof in nature, that vegeta¬ 
tion not only can , but does obtain food from th%atmos- 
phere, the proportion of course, varying with circum¬ 
stances, in some instances all. Of the latter, the most 
common example is the lichen that clings to, and sur¬ 
vives on the barren rock; but to this may be added cer¬ 
tain mosses, ferns, and the Epiphytes of the tropical re¬ 
gions, that exist entirely on the atmosphere, while it is 
well known that a branch of live-forever, (Sedum tele- 
phium) if fastened to a dry, hard wall, will grow an en¬ 
tire season. 
These examples, in connection with others unnecessary 
to mention, are proof positive that plants do draw on the 
atmosphere for a support; but independent of these, the 
simple fact, that continuous, uncropped vegetation al¬ 
ways generates fertility, is equally conclusive evidence. 
Indeed, it is highly probable that we are indebted to this 
wise provision of Deity for the very existence of verdure 
itself. For at the dawn of vegetatiou, the earth must 
have been destitute of vegetable matter j hence plants 
were driven to the necessity of looking elsewhere for their 
organic constituents, and had they been forbidden access 
to the great atmospheric ocean that surrounded them, 
they must have perished. It is to this law of nature that 
we are indebted for those extensive deposits of peat that 
are scattered over the earth’s surface, and those moun¬ 
tain masses of mineral carbon that lie buried beneath it. 
Their existence in the absence of this law, would present 
a problem that would defy solution. 
In fact, there is scarcely room for a reasonable doubt 
of its truth, for the whole economy of vegetation is cor¬ 
roborative of the principle that the atmosphere is the 
great storehouse, from whence its supplies have been 
and are drawn. Without admitting its correctness, it 
would be impossible to account for the circumstance that 
a forest of long standing will have enriched the soil, and 
at the same time accumulated in its gigantic trees an im¬ 
mense amount of organic matter. Taking the position 
of the writer of the foregoing extract, it would be one 
of the most impoverishing processes imaginable, and all 
newly cleared lands would require long nursing before 
they could be fully resuscitated and restored to their 
original fertility, prior to the exhausting operation of 
rearing a huge forest, that drew its entire support from 
the soil on which it stood. 
But science has rendered the idea that observation up¬ 
on the operation of nature, would seem to establish, 
perfectly consistent, by revealing to us the composition 
of the vegetables and the atmosphere. It has taught us 
that the four organic constituents of plants, carbon, hy¬ 
drogen, oxygen, and nitrogen, that constitute from eighty- 
eight to ninety-nine per cent of every vegetable substance, 
exist in the atmosphere in an available form. 
The oxygen and nitrogen constitute the greater por¬ 
tion of it, being mechanically intermixed in the propor¬ 
tion by weight, of 77 parts of the former to 23 of the 
latter. The carbon exists in the form of carbonic acid 
in .small and variable quantities dependant upon local 
causes; while the hydrogen is found in combination with 
oxygen and nitrogen in the form of aqueous vapor, and 
slight traces of ammonia. Thus, the organic elements 
of plants are found in the air in inexhaustible quantities, 
for the carbonic acid, aqueous vapor and ammonia, are 
constantly being eliminated from the surface of the earth 
by evaporation, combustion and decay. These elements 
may be taken in, either by the leaves or rootlets. In the 
leaves by direct contact, in the rootlets by cool currents 
of air condensing the vapor, that carries with it in its 
fall, common air, carbonic acid and ammonia. Let it 
enter either way, of course the atmosphere is the source 
1 of supply. 
I do not mean to be understood to say that all plants 
obtain all of then* organic support in this way, but that 
all do some, and a few classes of simple organization, do 
all. 
The case supposed by the writer, “ to demonstrate the 
correctness of his idea,” it strikes me, is not as conclu¬ 
sive as he assumes. The fact, that a huge oak, or hill of 
corn, will not thrive on a house top, or “sterile spot in 
the middle of a rich prairie,” is not evidence of the cor¬ 
rectness of his position, but simply proves that they are 
unable to draw directly from the atmosphere their entire 
support, but require access to other supplies that were 
originally drawn from the air. 
Neither can we suppose there to be any material dif¬ 
ference between the composition of the atmosphere in 
the center of a prairie of 50,000 acres, and that without its 
circumference; for air is of so buoyant a nature that it 
is thrown into currents by inconsiderable causes, that 
tend to produce an equalization. 
I consider also that there is a wide difference in the 
influence of the atmosphere on animal and vegetable life. 
The former subsists on the latter, while the latter draws 
most of its nourishment either directly or indirectly from 
the atmosphere. We may safely assert that animal life 
receives none of its nutriment from the air, (unless it be 
a small per centage of oxygen,) for it is inhaled only by 
the lungs, and that is not the proper channel for food to 
enter. What the precise office of respiration may be, it 
is perhaps impossible to ascertain, but it is at least a very 
plausible conjecture to suppose one of its main objects is 
to generate animal heat. 
Combustion is always attended with a rise of tempera¬ 
ture, and the slow combustion of carbon constantly going 
on in the lungs, must be attended by the same. In a full 
grown man in health, about half a pound of carbon is 
consumed every 24 hours, and exhaled in the form of 
carbonic acid, while a small quantity of oxygen is retain¬ 
ed and enters into the circulation of the blood. 
Now, in corroboration of this supposition, we have be 
fore us the fact, that men in extremely cold latitudes 
require a more carbonaceous diet than in warm ones. 
For example, the Esquimaux tribes, and those who navi¬ 
gate the polar seas, find that fat and oily food is not only 
heartily relished, but exceedingly conducive to health; 
