Fossil Vegetation of America. 371 
largely in the general advance of natural history, and, in con- 
sequence, to shed light on many abstruse and doubtful points 
of geology. 
That the nutritious vegetation of the present day is chiefly 
a fuel which, by a process of combustion, builds up man and 
other animals, and that the portion of this vegetation not formed 
for nutrition is still but fuel to be burnt during its decay by 
the oxygen of the atmosphere, are well-founded doctrines 
lately promulgated by Liebig, by Dumas, and Boussingault. 
From the “ Balance of Organic Power,” of the two last authors, 
I make the following short extracts : ; 
- * Light arrives, and, with the concurrence of carbonic acid 
_ nd nitrate of ammonia, the vegetable world, the grand pro- 
ducer of organic matter, is developed. Plants further absorb . 
the chemical force, which reaches them from the sun, and 
enables them to decompose carbonic acid, water and ammo- 
nia; plants are embodiments of a reducing power of greater 
virtue than any other that is known, for no other will decom- 
pose carbonic acid in the cold." 
in. *In our eyes, therefore, the vegetable world con- 
stitutes an immense magazine of combustible matter, destined 
to be consumed by the animal world, and in which this last 
finds the source of the heat and locomotive power, which it 
turns to account," — — 
But as, with the exception of a few mollusks, which might 
have fed on fuci abundant in a fossil state, animals did not 
exist during the growth of the vegetation of which the coal is 
ormed, the mind is inevitably led to the following reflection. 
That the vegetables of this period, not being intended for 
conversion into the higher state of animal organization, would 
Probably consist of such as were least fitted for this purpose. 
dingly, we find them akin to our present families of 
Ycopodiaceæ, Equisetacez, none of which are nutritious, of 
Filices, the root of only one of which is edible (Pteris escu- 
lenta,) of Coniferæ, of which the kernels of the seed alone are 
"Sed. "The character of the so-called Gramineæ, of this 
