4 INTRODUCTION. 



of forest and garden, from the visible display of green 

 foliage and rainbow-coloured blossoms around us, and 

 contemplate the silent and wonderful economy of that 

 other world of minute or invisible vegetation with which 

 we are so mysteriously related, though we know it not. 

 There is something exceedingly interesting in tracing 

 nature to her ultimate and simplest forms. The mind 

 of man has a natural craving for the infinite. It delights 

 to speculate either on the vast or the minute ; and we 

 are not surprised at the paradoxical remark of LinnEeus, 

 that nature appeared to him greatest in her least pro- 

 ductions. 



These plants once occupied the foremost position in 

 the economy of nature. Like many decayed families 

 whose founders were kings and mighty heroes, but whose 

 descendants are beggars, they were once the aristocracy 

 of the vegetable kingdom, though now reduced to the 

 lowest ranks, and considered the canaille of vegetation. 

 Geology reveals to us the extraordinary fact, that one 

 whole volume of the earth's stony book is filled almost 

 exclusively with their history. Life may have been 

 ushered upon our globe through oceans of the lowest 

 types of confervas, long previous to the deposit of the 

 oldest palaeozoic rocks as known to us ; and for myriads 

 of ages these extremely simple and minute plants may 

 have represented the only idea of life on earth. But 

 passing from conjecture to the domain of established 

 truth, we know of a certainty that at least throughout 

 the vast periods of the carboniferous era, ferns, mosses, 

 and still humbler plants, occupied the throne of the vegeta- 

 ble kingdom, and, by their countless numbers, their huge 



