OCEANOGRAPHY OF SEA OF GREENLAND—DAMAS. 381 
meters. On the other hand, there is an absolute difference between 
the central waters and those of the polar current in the Greenland 
Sea. This fact is evidently explained by the circumstance that 
down to 800 meters the superficial waters of the polar basin can flow 
out freely. The deep-lying waters, as has been previously stated 
by Nansen and as confirmed by the Belgica, are different. a fact 
which can be explained only by the existence of a submarine relief 
uniting Spitzbergen and Greenland. To the explanation invoked 
by Nansen in favor of this hypothesis is added then the fact ascer- 
tained by the Belgica of the identity of the superficial waters, and 
one must suppose that this relief rises to within nearly 800 meters 
of the surface. 
It is to be noted that this conclusion rests upon the extreme ex- 
actitude to which the hydrographic observations of the expedition 
were carried. Modern oceanography has a second method for de- 
termining the zones of influence of marine occurrence. It consists 
of a study of the distribution of organisms which appear passively 
under their influence. The knowledge of the plankton has become 
in the last years the necessary complement of all oceanographic re- 
search. This point of view was not neglected during the campaign 
of 1905 of the Belgica. The naturalist of the party, M. E. Koefoed, 
had employed the best instruments for pelagic fishing, and obtained 
the first truly representative collection of the floating fauna of 
the polar current. It had the more value since it comprised not 
only the catches made horizontally by the aid of instruments of 
large size dragged at various levels, but also an important number 
of catches made by the aid of an excellent closing net invented by 
Nansen. It tells us as a result very exactly the composition of 
plankton in the Sea of Greenland and concerning the horizontal and 
vertical range of the principal pelagic organisms. 
But before utilizing the zoological facts thus obtained, for geo- 
graphic study, it is important.to determine in what proportion 
the divers species are influenced by marine currents. In this short 
résumé we will limit ourselves to describing some of the conclusions 
of general interest to which the study of the materials collected by 
the Belgica has conducted us. It will appear with a sufficient 
amount of evidence that the use of the plankton as an indication of 
the marine currents should be made with extreme care. It is known 
that various species of animals, belonging to very diverse groups 
(crustaceans, worms, ctenophores, coelenterates), have been con- 
sidered as characteristic of polar waters, and the conclusion is 
reached that their appearance in the lower latitude is indicative of 
the existence of waters coming from arctic regions. We are, never- 
theless, able to state, thanks to the pelagic catches of the Belgica, 
that the composition of the plankton in the Sea of Greenland was 
