322 Ancient Vegetation of the Earth. 
inhabitants ; and the vegetable kingdom, at that period, main- 
tained undivided sway over all the undeluged portions of the 
earth; upon which it seems to have been called to play another 
part, in the economy of Nature. 
- We cannot doubt, in truth, that the immense mass of carbon — 
accumulated in the bosom of the earth, in a state of coal, and 
which is the product of the destruction of those vegetables which 
grew at that ancient epoch, upon the surface of the globe, has 
been imbibed, by those vegetables, in the carbonick acid of the 
atmosphere—the only form under which carbon, not derived from 
the destruction of preéxisting, organized beings, can be absorbed 
by plants. 
Now, a proportion, even very feeble, of carbonick acid, in the 
atmosphere, is generally an obstacle to the existence of animals, 
and particularly of the most perfect classes of them, as mammif- 
ers, and birds; while, on the contrary, this proportion is highly 
favourable to the growth of vegetables: and if we admit that 
there existed a proportion very much greater of this gas in the 
primitive atmosphere of our globe than the present atmosphere is 
found to contain, we may consider this one of the principal causes 
of the powerful vegetation of these ancient epochs. 
This collection of vegetables, so simple, so uniform, and hid 
would consequently have been so little fitted to furnish suitable 
aliment for animals of diversified structure, such as those existing 
at the present day, in purifying the atmosphere of the carbonick 
acid which it then contained in excess, would have prepared the 
conditions necessary to a creation more varied: and if we still 
wish to indulge that sentiment of pride which has caused man to 
assume that all in nature has been created exclusively for him, 
we may suppose this primitive, vegetable creation, which prece- 
ded, by so many centuries, the appearance of man upon the earth, 
was, in the economy of nature, designed to prepare the atmos- 
pherick conditions necessary to his existence, and at the same 
time to accumulate those immense masses of éombustibhes which 
his industry was in future time to apply to his necessities. 
But, independently of this difference in the nature of the 
atmosphere, which the formation of these vast depots of fossil 
carbon renders extremely probable, may not the nature of the 
vegetables themselves, that have produced them, furnish some 
data upon the other physical conditions to which the surface of 
