Caroline L e e g a a r d. 



Table I. The Positions of the Stations. 



The samples were for the most part taken from the following ilepths: mètres, 

 5 m., 10 m., 20 m., 30 m., 40 m., 50 m.. 60 m., 80 m., 100 m. 



At those stations where the depth did not reach 100 mètres (Table I), the deepest 

 samples were taken a short distance from the bottom. At the station F 74 the deeper 

 samples are wanting. 



Almost all the samples were mnch fonled by détritus brought into the sea by the 

 rivers. On account of the shallowness of the water the wind and waves easily stir up 

 the deposits of the bottom, so that the plankton samples will not be as clean as those 

 from the open and deep ocean. 



The centrifugal method lias been employée!. Samples of 50 ce, 25 ce. or 10 ce. 

 being centrifugated the numbers of individuals (cells) hâve been counted. In the tables 

 containing the results of the observations ail records are given in numbers of individuals 

 (cells) pi-, litre. At the head of the tables are given the depth of the sample and some 

 hydrographical data, viz: température, salinity and oxygen tension, all taken from the 

 „Jahrbuch 1912" by Dr. Kolf Witting (Finländische hydrographisch-biologische Unter- 

 suchungen. No. 12). Below the hydrographical data are given the quantifies of each 

 water sample examined. In some instances it has been necessary to count the contents 

 of two quantifies of the same sample. When in the tables two values are given, as foi' 

 instance 50 (10), this indicates that a few species which occur very abundantly hâve 

 been enumerated in a sample of 10 ce, while ail the others hâve been enumerated in 

 a sample of 50 ce. One special diatom, namely Achnanthes taeniata, occurred so abun- 

 dantly, that the examination of this species was rather difficult even in such a small quan- 

 ti ty of water as 10 ce. . 



The material will be arranged in the following way: 



Chapter I. The Separate Species and their Distribution. 



Chapter II. Survey of the Stations. 



Chapter III. Remarks on the Conditions of Life and the Quality of the Plankton. 



Of course this one series of samples taken at almost the same time cannot give 

 absolutely reliable information as to the habits of life of the différent species. We must 



Tom. XLVIII. 



