PREFACE 



FT is now twelve years since the publication of the author's ' Treatise on 

 British Freshwater Algae' and several years since that work was sold 

 out. Since the time of its publication great strides have been made in our 

 knowledge of many groups of Algaa and it is now proposed to replace the 

 'Treatise' by two works of which this is one. The present volume, contributed 

 to the series of Cambridge Botanical Handbooks, is a biological account of all 

 the Algae included in the Myxophyceae, Peridiniese, Bacillariere and Chloro- 

 phycea^, both freshwater and marine, and therefore from the biological aspect 

 more than covers the Alga3 dealt with in the ' Treatise.' The author has 

 also in preparation a distinct work which will be a complete systematic 

 account, with illustrations, of all the Freshwater Algae (with the exception 

 of Desmids and Diatoms) which are known to occur in the British Islands. 

 This is a task of some magnitude and will still take some time to complete. 



An endeavour has been made to be impersonal throughout this volume, 

 but the whole work must of necessity be largely the embodiment of the 

 views of the author. 



A chapter has been devoted to the Peridiniea? because these organisms 

 are important as ' producers ' of organic substance, especially in the marine 

 plankton, and they store starch and oil as food-reserves ; moreover, no 

 comprehensive modern account of the group has previously been published 

 in an English text-book. It might be suggested tha f 403 



have been included in this volume, since t^ r 411 



' producers,' but the immense addition ' ill 



these organisms certainly necessil UTION OF F RESH WATER ALGA: 418 



The greater part of thi^ ia tions . 41!) 



group that the authors of Irrorated Rocks . J 



of new detail^aatic Associations . '- :? 



is diF ADDENDA .... 452 



se ' INDEX . 455 



45351 



