SOUTHERN CULTIVATOR. 
339 
such a sense as lias lieretofora prevailed respecting this 
subject. 
We know that humus is produced by the fermentation 
of the constituent parts of vegetable and animal manures; 
and we also know that the jdants grow luxuriantly in 
such soils as are well manured, and are, consequently, 
rich in humus. Our present inquiry, however, does not 
concern the favorable effect of manure and humu.s on 
vegetable life in particular, but we are simply to inquire 
wliether the carbon of humus is used for yielding the car- 
bon contained in plants or notl 
The favorable effect of manure, and especially of humus, 
does not here prove that it is its carbon which produces this 
effect; inasmuch as humus contains many other things 
besides carbon, which might possibly be valuable to the 
plant. Humus, such as it is found in the earth, can give 
no aid in procuring carbon for the plants, or, more pro- 
perly, the carbon in the plants is not received by them in 
the form of humu.s or a humusate; which we will now 
endeavor to es ablish. 
We may sow seed in pure sand and be able to rear 
plants which, indeed, have not the power of developing 
themselves perfectly, l>ut in which we, nevci theless, may 
trace a content of carbon, which can in no wise be attri- 
buted to the absorption ot humus from the eartli, just be- 
cause there is none sucli in the earth. It might here be \ 
said, that' the seed may itself generate humus; but if we 
even take this for gratited, there' will he nothing gained 
by it ; foe tjiere is more carbon in the plant than there was 
in (lie seed origiiKtlly. There must, consequently, be 
another source to tlie vegetable carbon, than humus. And 
{IS regards liyacinths, iei.s well known that the bulbs of 
these plants may, without humus, in mere water, be made 
to yield a ju'ofusion of leaves, stehis and flowers, the carbon 
of which cannot have originated from present huii'.us, and 
must, consequently, be talxen froih elsewhere, i>ut in 
maintaining the fact that, .vegetable carbon must have 
another .source than humus, we are not limited to sucji 
in.signiticant tests ; on the contrary, nature, does, in this 
respect, oiler us very considerable and proper proof. 1 
mean our immense fore.st 3 . 
Let us imagine ourselves as bejng in a forest on sand- 
stone rocks, where the pine attains to a powerful growth, 
and we shall here and there observe, in the cracks of 
w'holly naked rocks, a strong pine-stem shoot forth, which 
is far from being rooted in humus soil. From whence, it 
will be asked, do these*]Dlants take their carbon'? for there 
is no humus in the soil, or in every case so little, that its 
carbon does not amount to more than a few ounces, while 
the weight of the carbon in a single tree amounts to hun- 
dreds. Here, too, we must look for some other source 
to the cari.)on, for it cannot be humus. And, as it is with 
a single tree, so it is with forests of many mile’s extent. 
The humus, which is tlicre found in the earth, isevidently 
produced by fallen leaves, twigs and branches, and by 
the ci)j»picc, which grows at the bottom; all the carbon 
hereiti must, therefore, still he ascribed to the forest tree’s 
content thereof; and now the question is asked : From 
whence have all the trees of the forest deriveil their car- 
'Ixui'? The answer is now and ever: in no wise from the 
humus of the soil ; for the forest, instead of decreasing, in- 
•creascs in humus, by means of the vegetable extension. 
Consider, moreover, the meadows. Wh.at an amount of 
carbon is annually taken away in the form of hay, and 
what are we then doing towards giving the earth restitu- 
tion for the carbon of which we have deprived it, 
and which was present in it as liumus'? Perhaps some 
-one will answer : that the grass-roots remain in the soil, 
and that humus is formed by their decomposition; so far 
so good ! but from svhence comes the carbon which these 
vToots contain 1 
1 have several times, in the vicinity of the Alps, wit- 
nessed the mowing of grass, where the cattle could not 
reach it on account of the steepness of the place. These 
places, consequently, are yearly deprived of a certain 
quantify of carbon in the form of a hay, and are, in no 
manner, compensated therefor. This carbon must, accord- 
ing to the prevailing opinion, have been present in the 
soil humus. But it is not difficult somewhat nearly to de- 
termine the quantity of humus in the soil of these steep 
mountains. It could not be large; for everywhere the 
naked rock was visible. But take any number, however 
large, we are enabled to calculate how much carbon it 
contains, and it is clear as day, that if the carbon of the 
hay is derived from the humus, there must finally come 
a time when carbon will be v/anting, because the humus 
is consumed, and with it the source of carbon dried up. If! 
now, taking such suppositions for granted, would have said 
to the shepherd, who went to his home with a heavy grass- 
burden, he whose fiither and grandfather already reaped in 
this place, and whose children and children’s children 
will do the same thing;, if I now said to him -.-—“Friend ! 
you are annually coming down with a large qtKiniity of 
grass ; see that you carry humus up there, or you will 
soon have a sorry crop!” what would he have answered 
me ”1 Sure, he would have at least considered me a fool. 
Every one would Imve agreed with him, and yet I strictly 
adhered in my remark to tlie maxim, that the carbon of 
the grass was owing to the humus in the soil. 
IVIoreover, do not believe that the humus in such manure 
cfs we carry out into our fields, contains so much carbon 
as we annually take away again in the form of grain. It 
will undoubte'dly seem so to seme, who confine them- 
selves to experience, from which they know, that he who 
manures well reaps well. And still they are mistaken ! 
Hcrtf, too, the carbon of the crop exceeds the carbon of the 
manure — a fact which can, in no way, be doubted, inas- 
much as it i.s founded on chemical analysis of both manure 
and crop. Thus, even if it is admitted that all the humus of 
the manure has relinquished its carbon to these plants, 
there must nevertheless be some other source of the car- 
bon. 
Direct experience, therefore, speaks against the idea of 
humn.s being used as such for the purpose of yielding car- 
bon to the plants. But we may employ the same proof 
in still another way, and even admit, although contrary to 
the most decisive analyses, that the crop contains no more 
carbon than was found in tf.e manure, or even less. 
When humus, namely, either as such, or as a humusate, 
is to be absorbed by the plant in order to be. decomposed 
and yield its carbon, then it must evidently be dissolved 
in water, inasmuch as iiccordiug to experience solutions 
only of one or other body can be absorbed by the plant. 
But here we immediately meet with new inconveniences, 
while humus is dissolved with great difficulty only, and 
there being foftnd no humusates which can easily be dis- 
solved in the soil. For, even supposing that some soil 
may contain so large an amount of humus as to make its 
carbon more than sufficient for satisfying the plant’s de- 
mand on carbon, then a quantity of humus corresponding 
to the requirements of the plant, will, nevertheless, need 
more water for its solution than the usual quantity of rain 
can yield. Thus, it is evident that the humus of the soil 
cannot, as such, be absorbed by the plant in a quantity 
sufficient for yielding carbon. 
When, now, we are able to show that plants may pro- 
duce carbon without the presence of humus in the soil; 
that, in many cases, the plant contains more carbon than 
the humus of the soil ; that grains alw'ays contain more car- 
bon than the manure; that two soluble humusates are not 
easily found in the soil ; that such humusates as are with 
difficulty soluble, require for their solution more water 
than falls in the form of rain ; and finally, that the humus 
of the soil, and, consequently, its carbon may become 
