454 
VEGETAULE OKIGIN 
the simpler forms which predominated through 
the two preceding periods. Smaller Equisetacese 
also succeed to the gigantic Calamites ; Ferns are 
reduced in size and number to the scanty propor- 
tions they bear on the southern verge of our tem- 
perate climates ; the presence of Palms attests 
the absence of any severe degree of cold, and 
the general character marks a Climate nearly 
approaching to that of the Mediterranean. 
We owe to the labours of Schlotheim, Stern- 
berg and Ad. Brongniart the foundation of such a 
systematic arrangement of fossil plants, as ena- 
bles us to enter, by means of the analogies of 
recent plants, into the difficult question of the 
Ancient Vegetation of the Earth, during those 
periods when the strata were under the process 
of formation. 
Few persons are aware of the nature of the 
evidence, upon which w'e have at length arrived 
at a certain and satisfactory conclusion, respect- 
ing the long disputed question as to the vegetable 
origin of Coal. It is not unfrequent to find among 
whose seed is made up of tw’o lobes, as in the Bean and Coffee 
seed. The stems of Monocotyledonous Plants are all Endogenous, 
1. e. increase from within by the addition of bundles of vessels 
set in cellular substance, and enlarge their bulk by addition 
from the centre outwards, e.g. Palms, Canes, and Liliaceous 
plants. The stems of Dicotyledonous Plants are all Exogenous, 
i. e. increase externally by the addition of concentric layers from 
without; these form the rings, which mark the amount of annua' 
growth in the Oak and other forest trees in our climate. 
