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B. The Plankton work of the International Investigation 

 of the Sea in the years 1902—1912 



by 

 C H. Ostenfeld. 



1. Introduction. 



The study of the marine plankton, i. e. the organisms floating freely in 

 the sea, as well as of the animal and plant life on the bottom of the sea, is a ne- 

 cessary part of any close study of the fish-fauna of the sea, since the plankton 

 and the organisms of the sea-bottom form the basis of all fish-food, and such 

 studies have therefore been included from the beginning in the work of the In- 

 ternational Investigations of the Sea. But the plankton organisms are also of 

 importance in another way: Being borne along the in water without resistance, 

 they follow the course of the ocean currents, thus serving as an aid to the study 

 of hydrographical conditions. There are thus two sides of the study of plank- 

 ton, which, as it were, connects the hydrographical investigations with those 

 having regard to fishery. 



In the programme which forms the basis of the activity of the Interna- 

 tional Investigations of the Sea (The Christiania Programme) the plankton in- 

 vestigations will be found mentioned both in connection with fishery-biological 

 work and that of the hydrographical department, the former also including in- 

 vestigations as to the bottom flora and fauna. Looking back upon the work 

 carried out in the furtherance of these various investigations during the past 

 ten years, one is forced to admit, with all respect for the great amount done, 

 that much is yet needed before completion is attained. As regards the inve- 

 stigations on the bottom organisms, there are but few of them which have 

 reached completion; at any rate not much has been published on the subject. 



It is otherwise with regard to the plankton. At the commencement of 

 the international co-operation, there were only some minor parts of the area 

 as to which anything was known of the plankton fauna and flora. It was there- 

 fore necessary, first of all to obtain more comprehensive knowledge as to what 

 animals and plants were to be found living in the sea water in all the extensive 

 area to be embraced by our investigations; further, it was necessary to invest- 



