OBSERVATIONS IN THE NORTHERN REGION 30? 



The results of these repeated cruises were very valuable in giving a complete picture 

 of the annual cycle in the Northern Region. The Intermediate and Southern Regions 

 were reached only from January to March 1939, when the results confirmed our previous 

 findings. It also became clear that the abundance of Phaeocystis, particularly in the 

 Intermediate Region, was confined to the period immediately after the break-up of the 

 pack-ice. In the Northern Region the quantitative phytoplankton cycle followed a 

 course we expected to find normal from our earlier and more widely dispersed obser- 

 vations, except that the maximum was rather later. Apparently the season 1938-9 was a 

 rather ' late ' year, as instanced also by the northerly position of the ice-edge as late as 

 December. 



DESCRIPTION OF THE OBSERVATIONS OBTAINED 



THE NORTHERN REGION 



The seasonal variation in pigment content of the phytoplankton of the Northern 

 Region, as indicated by meaning all our available estimations at mean dates, is shown by 

 the figures in Table i, and also in graphic form in Fig. 10. It will be noted that the 

 November figure is lower than that for October, and that this is thought to be an 

 anomaly due to the limitations of the data, and not representative of the true state of 

 affairs. The majority of our November figures were derived from the part of the Northern 



Table i 



Region lying south of the Indian Ocean, where we have twice observed that the main 

 increase seems to take place rather later and more suddenly than elsewhere (cf. 

 Itinerary). The October figures, on the other hand, were widely distributed. There is 

 little doubt that if more widely distributed observations for November were available, 

 the shape of the graph would approximate to that shown by the pecked line, over the 

 period in question. As already remarked, it does not seem advisable to regard the area 

 south of the Indian Ocean as essentially different from the rest of the Northern Region 



