58 
THE FOLIAGE— AND ITS FUNCTIONS. 
condensed water, the dry plant will continue to flag, till its soil receive and imbiH 
to its centre that quantity of water which its specific temperament requires. 
Herein also, the real skill and discrimination of the gardener are brought to th< 
test ; for, as plants differ much in their requirings, a great degree of knowledge am 
judgment are called for, otherwise, one subject may he swamped, while another ii 
scarcely kept alive. 
One more quotation, and then, having adduced evidences of the possible fallacy 
of modern theorists, we will, in fairness, give them every advantage which our owi 
observation enables us to bring forward. 
In proof, as it is supposed, that carbon is derived from the atmosphere, we read 
that, “ It is now pretty certain that plants generally derive their carbon from th< 
air. A forest in Scotland, which was planted fifty years since, now contains mor< 
charcoal than it did at the commencement of the period.” — (Have not all the leave 
fallen yearly, and by decay produced a blackened earth?) — “ Nitrogen, in the forn 
of ammonia, is also derived from the air to a great extent, being brought down to 
means of rain. It (ammonia) has been detected in rain-water, when sought for, ant 
likewise in snow, and is thus known to exist in the air. Whether all plants derivt 
all the nitrogen they want from the ammonia of the air, is another question ; it ii 
not a well settled point, and we want agricultural experiments to decide it.” 
This closing and modest addition, is conclusive : — an hypothesis exists — it is o 
recent date — proofs are wanting ; therefore the whole rests upon a conjectural basis 
The lecturer, as we have seen, asserts that ammonia exists in the air ; and that rail 
and snow conduct it to the earth. Direct experiment has, really, proved this fact 
but, what then ? Admit that every shower shall so convey a portion of that ammonia 
which had been received into the atmospheric volume, during the decomposition o 
animal matter, and the exhalation of ammoniacal gas from heaps of manure, and thi 
like fermenting substances ; yet, if it fall to the ground, and soak into the soil witl 
the rain or snow, which had been its solvents, does the theory of absorption by th< 
leaves receive any support from the admission? On the contrary, the ground 
becoming the recipient, we should rather be inclined to think that the fluid ammonia 
so situated, must enter the organism through the channels of the roots. 
Thus far, doubt has been maintained, on the ground of what appears to to 
fallacious experiments , conducted upon artificial principles. But, if we recur to pur 
nature, free from the experimentum crusis of the laboratory, and its death-dealinf 
gases, facts may be appealed to, that, to say the least of them, will confer probability 
upon the modern theory. First, then, there are numbers of plants, wild weeds o 
the field, uninterfered with by man ; and others, cultivated as food or fruit, whicl 
produce a system of foliage, so vast, so infinitely extended, when compared with tto 
stems, that it is scarcely possible to refer to any other channels of nutriment thai 
those of the leaf-pores or stomates. Take, as one example, the common duckweed 
and compare its hair-like , slender stem with the numerous thicker branch-stalk 
and their thousands of appendant leaves. As another example, look at the Cucumber 
