68 



DISCOVERY REPORTS 



THE PHYSICAL ENVIRONMENT OF THE 

 ANTARCTIC PLANKTON 

 A summary account of the hydrology of the Atlantic sector of the Antarctic and the 

 Bellingshausen Sea has been published by Mr G. E. R. Deacon (1933), and I am 



Fig. 1 . The Atlantic sector of the Antarctic, showing stations at which N 100 B samples were taken. Stations 

 included in intensive work around South Georgia and in the Bransfield Strait, and a line of close stations off 

 Adelaide Island, are omitted. Surface currents are indicated by arrows. 



indebted to him and to Mr A. J. Clowes for much valuable information. There are 

 four primary divisions of the oceans of the southern hemisphere : the Antarctic, sub- 

 Antarctic, sub-Tropical and Tropical Zones. The Antarctic Zone is characterized by 

 a cold, poorly saline surface layer of an average depth of about 200 m. This surface 

 water flows away from the melting pack-ice to which its low temperature and low salinity 



