INTRODUCTION 9 



point for a sufficient length of time to win their confidence 

 might add much to the information here brought together ; but it 

 should be borne in mind that indirectly they possess the highest 

 value, since lichens, Bryophytes, and the fern allies are the 

 earliest soil formers, while the marine algas furnish food for fish, 

 and thus, ultimately, for man. 



