Introduction. 



During the years 1901 and 1902 the examination of plankton collected at thc two 

 stations oii the Avest coast of Sweden, Väderöboda and Måseskär, has been continued as 

 during tlie foregoing years. Also the North Sea has been explored, as far as concerns 

 the sui-face, in August and November 1901, February and May 1902. The Skagerak has 

 been throughout examined by the Swedish hydrographic-biological commission in August 

 1901 a,nd February 1902 and in a less complete manner in July 1902. 



As the work of the international cooperation for the exploration of the sea com- 

 menced in August 1902 I wish here to complete my previous researches by publishing 

 the resuits obtained up to the date naiued. Liiter researches have been forwarded to 

 the Central Bureau of the international cooperation. 



Before entering upon the detailed report of the results obtained by my plankton 

 researches, I will treat of sorae (|uestions of a more general nature, especially as my 

 views concerning the distribution of plankton-organisms have recently been subjected to 

 criticisras by the Norwegian scientist Mr. Gran in his work »Das Plankton des Norwe- 

 gischen Nordineeres» Bergen 1 902. 



Already in his »Report on Norwegian marinc investigations 1895 — 7» (Bergen 1899) 

 Mr. GiiAN attacks my statement that the plankton-organisms continually drift with the 

 curi-ents to far distant regions and holds that the plankton develops on the spöts where 

 found and by the spiring of resting spores, eggs etc. I did not answer this criticisra as 

 I was convinced that widened experience would alter Mr. Gkan's views. This also seemed 

 to be the case, ms Mr. Grax in his »Hydrographic-biological studies of the Nort Atlantic 

 Ocean and the coast of Nordland,; (Kristiania 1900) professes views, which only slightly 

 dififer from my own. In his latest publication M. Gran returns to his old position. 



Mr. Grax's criticism concerns me in many points, both in his details and its prin- 

 cipal standpoint. To reply to all detailed remarks would require more time and work 

 than I can at present give to the matt er. It would be necessary for such a task to 

 deal with the whole, and at present very large, material of observations for a number 

 of plankton-organisms and to take in consideration the fresh and multitudinous facts 

 published in Gran's latest paper. Mr. Gran's data are unfortunately published in such 

 a way that they require rearrangement before they can be placed beside other observations, 

 a work requiring considerable time. Still, I have tried to arrange his data for 1901 with 

 my own, and the result will be found in the special part of this paper, l)ut for the 



