ITINERARY: THIRD COMMISSION 399 



We sailed to the south-west again early in August 1934, and obtained good evidence 

 of the negligible quantities of phytoplankton in winter in the Northern Region, on our 

 way to South Georgia. From 25 August to 3 September, in the South Georgia area, the 

 quantities were more than twice as great— still very small. During the following week 

 it was found that in the Scotia Sea the values, though lower than at South Georgia, 

 were double those obtained in corresponding latitudes in the open ocean a fortnight 

 earlier, but in the eastern South Pacific they were still negligible. 



Between 26 September and 12 October a double series of observations in the Scotia 

 Sea showed that the phytoplankton had increased to three or four times the values 

 observed earlier in September, though still poor when considered in relation to the 

 quantities to be found there later on, during the main increase. 



During the first half of November an extended series of observations was made in the 

 eastern South Pacific. The main increase seemed to be in progress from 2 November, 

 when the first estimation exceeding 1000 units of plant pigments per m.'' was obtained. 

 The values, however, were low even when compared with those for other oceanic 

 regions at this season. Possibly the weather conditions, which were exceptionally bad 

 throughout this cruise, may have been, in part, responsible for this. A uniform poverty 

 of phytoplankton in the eastern South Pacific seems to be the rule at all seasons, however, 

 when we compare the results with those from other areas. 



For the next two months the ship was engaged in carrying stores for the British 

 Graham Land Expedition, and in survey work round the South Shetland Islands. No 

 routine phytoplankton observations were made, but interesting observations on the 

 exceptionally dense neritic development at Deception Island and in de Gerlache Strait 

 were possible on two occasions. 



At the conclusion of the survey programme a line of stations was worked from the 

 South Orkney Islands northwards across the Scotia Sea, beginning on 23 January 

 1935. At the two southernmost stations, nearest to the shoal water of the Scotia Arc, 

 a very rich neritic phytoplankton was encountered. Farther north the quantities 

 observed were more moderate. About the beginning of February some moderate 

 hauls were obtained to the north of South Georgia, but east of the more southerly part 

 of that island the phytoplankton was poor. 



The work of the third commission was concluded by a long cruise eastward across 

 the Intermediate and Southern Regions of the Antarctic zone, south of the Atlantic 

 and beyond to 43° E, during February and March 1935. Some high values were 

 recorded in both regions up to the third week of February, but the phytoplankton was 

 evidently distributed very irregularly, with considerable evidence of heavy grazing 

 causing local scarcity. During the latter part of this cruise the values in the Inter- 

 mediate Region fell off indicating post-maximal decrease, while slightly higher values in 

 the Northern Region in March may have indicated the beginnings of the secondary 

 autumnal increase. On leaving Antarctic waters observations were continued north- 

 wards through the Mozambique Channel before the ship made her way home through 

 the Red Sea and the Mediterranean. 



