— 55 — 



and post-larval herrings 34 samples of micro-plankton have been preserved and 

 examined quantitatively. 



Scotland. 8) Samples have been collected during all cruises and are being 

 worked up quantitatively. 



Other plankton work: 

 Denmark. On the "Dana"-Expedition a large material of plankton has 

 been collected, viz: 



a) A series of water samples preserved with neutralised formaline, to be used for 

 the study of the nanoplankton by means of centrifuge and microscopical exami- 

 nation and counting. 



b) A large series of micro-plankton, both horizontal hauls and vertical hauls by 

 closing-nets (Nansen's pattern) were made. Most of the samples were examined 

 in living stage on board the steamer while working in the Caribbean Sea and 

 adjacent areas, and also in the Pacific (Gulf of Panama). 



c) Macro-plankton was collected in connection with other biological works. 



England. No work has yet been carried out in standardising methods and 

 gear. The plankton collected during the plaice-egg cruises in the winter 1920 — 21 

 has been studied in detail and a report is in process of completion. Regular collections 

 of macro-plankton have been made in connection with hydrographical work and the 

 capture of larval herring: 113 samples have been examined quantitatively and 124 

 qualitatively. A study has been commenced of the extent to which shoaling of 

 plankton occurs. 



Investigations into the plankton brought into the North Sea by the abnormal 

 influx of Atlantic water during 1921 have been carried out, with the result that 

 great quantities of the Atlantic pteropod Limacina lesueuri (d'Orbigny) were 

 recorded for the first time in the North Sea. 



Also a few specimens of young Peradis appeared for the first time on record. 

 Limacina retroversa, not usually abundant off our east coast, appeared in great 

 numbers. The Radiolarian — Acanthometron quadrifolia, a common Gulf stream 

 form, usually rare in the North Sea, occurred in enormous numbers. The medusa, 

 Tima bairdii, common off the Scotch coast, appeared to be unusually common 

 as far south as the Wash. 



During the hydrographical cruise from the Tyne to the Naze of Norway 

 in May 1922 similar investigations were carried out, but only a few Limacina lesueuri 

 were recorded. 



Finland. The special investigations of the littoral vegetation in the harboui^s 

 and environments of Helsingfors is completed and published. Similar researches in 

 Hangö and Ekenäs continued. The detailed investigation of the plankton in the 

 harbours and waters of Helsingfors is continued, and a study of the fluctuations of 



