TO 

 DR. ANTON HANSGIRG, 



OF THK ROYAL-IMPERIAL UNIVERSITY 



OF PRAGUE, BOHEMIA, 



IN RECOGNITION OF HIS EARNEST RESEARCHES 



AND VALUABLE CONTRIBUTIONS TO THE 



LIFE-HISTORY OF FRESH-WATER ALG^E, 



THIS VOLUME IS RESPECTFULLY 



DEDICATED 



BY HIS FRIEND AND CORRESPONDENT, 

 THE AUTHOR. 



