10 INTRODUCTION. 



ascertained, from the soundings obtained during the in- 

 vestigations connected with laying the electric telegraph 

 cable between Ireland and Newfoundland, that the floor 

 of the Atlantic is paved many feet deep with their sili- 

 cious shields, preserving in all their integrity their won- 

 derful shapes, notwithstanding their extreme delicacy and 

 minuteness, and the enormous pressure of the vast body 

 of water which rests above them. Such is the wide 

 space which these organisms occupy in the fields of nature 

 a prominence which is surely sufficient to redeem them 

 from the charge of insignificance. They are inferior in 

 majesty of form to palms and oaks, but in their united 

 influence it is not too extravagant to say that they are 

 not less important than the great forests of the world. 



This vast profusion of minute and humble vegetable 

 life serves the obvious purpose of preparing the way for 

 higher orders of vegetation. Nature is incessantly work- 

 ing out vast ends by humble and scarcely recognisable 

 means. The features of the earth are being continually 

 altered by the germination and dispersion of the algae, 

 mosses, and lichens. Bare and sterile mountains are 

 clothed with verdure ; rocks are mouldering into soil ; 

 seas are filling up ; rivers and streams are continually 

 shifting their outlines ; and lakes are converted into fer- 

 tile meadows and the sites of luxuriant forests, by 

 means of the vast armies of nature's pioneers. Hard 

 inorganic matters are reduced to impalpable atoms ; 

 waters and gases are decomposed and moulded into new 

 forms and substances having new properties, by vegeta- 

 ble growth. Minute as these plants are, they are inti- 

 mately related to the giant forms of the universe. It 



