INTRODUCTION. 
IT cannot have escaped the notice even of the 
most unobservant, that the tendency to vegetate 
is a power restless and perpetual. It has been in 
operation from the earliest ages of the earth, ever 
since living beings were capable of existing upon 
its surface, as evinced by the fossil remains found 
in the most ancient rocks. Like a palimpsest, the 
successive strata of the earth have been covered 
with successive races of plants. Wherever an 
igneous rock was upheaved into the sky by some 
internal convulsion, its bare sides and summit were | 
speedily covered with vegetation ; wherever the 
water retired, leaving its sediment behind, the dry 
_ land thus formed became, in a wonderfully short 
space of time, clothed with verdure. From pole to 
pole, each stratum of soil, as soon as deposited, 
was adorned with a rich exuberance of plant-life. 
Noris the layer of Nature’s floral handwriting which 
A 
