THE PHYTOPLANkTON OFTHE ENGLISH 

 LAKE DISTRICT. 



(plates v., VI. and vii.). 



Wm. west, F.L.S., 



AND 



G. S. WEST, M.A., D.Sc, F.L.S., 



I.— INTRODUCTION. 



During an investigation of the British freshwater phyto- 

 plankton, material^has been collected on several occasions from 

 the various lakes of the English Lake District. These collec- 

 tions were made as part of a general comprehensive scheme for 

 the investigation of the plankton of the British lakes. We have 

 been enabled to carry out this research during the last few years, 

 chiefly by means of several grants from the Government Grant 

 Committee of the Royal Society.* 



The general Alga-flora of the English Lake District is fairly 

 well worked out. The earliest paper of importance was a list 

 of Desmids found in the neighbourhood of Windermere by 

 Bissett,f and this was followed by two papers by A. W. Ben- 

 nett. J Wej^have ourselves explored the greater part of this 

 area very thoroughly for Algae of all kinds, and have at different 

 times contributed papers dealing either exclusively or partially 

 with the Algae of the English Lake District. || 



The first collections of plankton were made in June 1903, 

 and we had the advantage of beginning this plankton investi- 

 gation after having previously acquired a very complete know- 

 ledge of the general Alga-flora of the bogs, streams, pools, and 

 lake-margins. This has enabled us to thoroughly appreciate 

 the differences between the phytoplankton and the general 

 Alga-flora, and to endeavour to find out something concerning 

 thejexisting relationships between them. 



Considering the size of some of the English lakes, they are 

 situated in a very compact area, the whole of which is incor- 



* A general summary of this work, treated largely from a comparative 

 standpoint, has quite recently been presented to the Royal Society. 



t J. P. Bissett, ' List of Desmidiea; found in gatherings made in the 

 neighbourhood of Lake Windermere during 1883,' Journ. Roy. Micr. Soc' 

 1884. 



+ A. W. Bennett, ' Freshwater Algae of the English Lake District, etc.', 

 ' Journ. Roy Micr. Soc.', 1886 ; ' Freshwater Algae of the English Lake 

 District, IL', ibid. 1888. 



II W. West, ' Alga; of the English Lake District,' ' Journ. Roy. Micr. 

 Soc," 1892 ; W. and G. S. West, ' New British Freshwater Algae,' ibid. 

 1894 ; W. and G. S. West, ' Notes on Freshwater Alga>, II.', ' Journ. Bot.', 

 XXXVIIL, 1900 ; III., ibid, XLL, 1903, etc. 



1909 March i. 



