COMPLEX HISTORY OF COy\L. 481 
of Structure, and by details of organization, which 
shew them all to be parts of One grand, and 
consistent, and harmonious Design. 
We may end our account of the Plants to 
which we have traced the origin of Coal, with a 
summary view of the various Natural changes, 
and processes in Art and Industry, through which 
we can follow the progress of this curious and 
most important vegetable production. 
Few persons are aware of the remote and won- 
derful Events in the economy of our Planet, and 
of the complicated applications of human In- 
dustry and Science, which are involved in the 
production of the Coal that supplies with fuel 
validate the certainty of our knowledge of the entire Flora of 
each of the consecutive Periods of Geological History, it does 
not affect our information as to the number of the enduring 
Plants which have contributed to make up the Coal formation ; 
nor as to the varying proportions, and changes in the species of 
Ferns and other plants, in the successive systems of vegetation 
that have clothed our globe. 
It may be further noticed, that as both trunks and leaves of 
Angiospermous dicotyledonous Plants have been preserved abun- 
dantly in the Tertiary formations, there appears to be no reason 
why, if Plants of this Tribe had existed during the Secondary and 
Transition Periods, they should not also occasionally have escaped 
destruction in the sedimentary deposits of these earlier epochs. 
In Loudon's Mag. Nat. Hist. Jan. 1834, p. 34, is an account 
of some interesting experiments by Mr. Lukis, on successive 
changes in the form of the cortical and internal parts of the stems 
of succulent plants, (e. g. Sempervivum arboreum) during various 
stages of decay, which may illustrate analogous appearances in 
many fossil plants of the coal formation. 
GEOL. T I 
