340 REPORTS ON THE STATE OF SCIENCE, ETC. 



FRESHWATER BIOLOGICAL STATION, WINDERMERE. 



Report of the Committee appointed to aid competent investigators to carry 

 out definite pieces of work at the Freshwater Biological Station, Wray 

 Castle, Westmorland (Prof. F. E. Fritsch, F.R.S., Chairman ; 

 Dr. E. B. WoRTHiNGTON, Secretary ; Prof. P. A. Buxton, Miss 

 P. M. Jenkin, Dr. C. H. O'Donoghue, Dr. W. H. Pearsall). 



During part of the current year the British Association's table at the 

 laboratory has been occupied by Mr. G. H. Wailes while working on the 

 planktonic Protozoa of Windermere. Mr. Wailes, formerly of Vancouver, 

 British Columbia, resided at Wray Castle in the autumn of 1937, and has 

 since received and examined samples of plankton collected each fortnight 

 by the Association's staff. During the last part of the year Miss Pennington, 

 of the Botanical Department, Reading University, has been appointed to 

 occupy the table, in order to work on the succession of diatoms and pollen 

 in cores raised from the bottom deposits of Windermere and other lakes. 

 It is yet too early to report on Miss Pennington's research, but Mr. Wailes 

 has drawn up the following short account of his study. 



Plankton Protozoa of Windermere. 



During a visit to Wray Castle in September, 1937, collecting was carried 

 out with the object of observing in a living state the planktonic species of 

 Protozoa occurring in Windermere, as a preliminary to tracing throughout 

 a complete year the seasonal changes that take place in the plankton in both 

 the north and south basins of the lake. Commencing on September 22, 

 fortnightly samples of preserved Windermere plankton have been received 

 and have been examined. They were obtained by hauling vertically a fine 

 meshed net from a depth of 40 metres to the surface. 



As a result of the collecting done in September, chiefly in the north basin, 

 the following species were observed which up to the present (June) have 

 not been recorded in the serial plankton gatherings, namely the Heliozoans 

 Acanthocystis spinifera and Raphidiophrys elegans, a small naked dinoflagellate 

 Gymnodinium pulvisculus, which, like others of that group, disintegrates 

 under the action of preservatives, and a small ciliate belonging to the 

 Tintinnioidae which proved to be an undescribed species and has since been 

 named Tintinnopsis wrayi (Ann. & Mag. Nat. Hist., May, 1938). 



The Protozoa present in the plankton during the period observed 

 (September to June) comprise two groups ; the first, consisting of the 

 Dinoflagellata and Dinobryon divergens, was absent from mid-November to 

 mid-February, whereas the other was persistent during the winter and 

 consisted of species of Rotifera, Vorticella, and an infusorian, Mallomonas 

 acar aides. 



Dinoflagellata comprised the species Ceratium hirundinella var. gracile, 

 Peridinium willei and Peridinium kincaidi (the last-named has previously 

 been recorded only from Alaska and British Columbia). Numerous cysts 

 of these species and individuals of P. kincaidi occurred until mid-November ; 

 thereafter no dinoflagellates were observed again until mid-February. By 

 March P. willei and P. kijicaidi had become equally plentiful. Rotifera, 

 represented by some seven or eight species, were numerous throughout the 

 winter ; they have been submitted to a specialist for specific determination. 

 The most notable feature of Windermere plankton was its different 



