INTRODUCTION 



The distribution of the Atlantic plankton organisms has hitherto 

 been examined by some expeditions, such as the Challenger and 

 National Expeditions and others. These however, only crossed the 

 Atlantic during certain seasons for a relatively short time, and in 

 different years. As the plankton follows the ocean currents and its 

 distribution is subject to continual changes, it is evident that the 

 knowledge thus obtained must be very fragmentary. In order to get 

 more complete information about this matter Professor 0. Pet- 

 TERSSON, Mr GusTAF Ekman and the present author planned a 

 systematical investigation of the waters of the Atlantic during the 

 space of at least one year, as far as temperature, salinity and 

 surface-plankton were concerned. To assist us in carrying out this 

 programme, we communicated with a number of ocean-liners and 

 other vessels and it affords us pleasure to state that the officers 

 were very willing to assist us in procuring samples for scientific 

 examination. Samples were taken once a day at least, in some 

 cases several times, with simultaneous observation of the temperature 

 of the water. The plankton was obtained by pumping water for 

 10 to 15 minutes at a time through a fine silk net, the small resi- 

 duinu being then transferred to a bottle containing alcohol. The 

 samples thus obtained were in most cases very small, but usually 

 sufficiently large to characterize the water. In some cases the 

 number of different species was astonishingly large. 



Furthermore we tried to get samples collected regularly at 

 certain fixed stations, as at Westmannao (S. Iceland\ the Faroes 

 and the Azores. 



To defray the expenses connected with these researches the 

 sum of 7,()(M) ki'onor was obtained from the fund »Lars Hiertas 

 minne>-, and for the publishing of the results by the »Goteborgs 

 Vetenskaps- och Vitterhets-samfund» ]\Ir August Hohss contributed 

 the sum of 3,000 kronor, which we here thankfullv acknowledge. 



