5 8 DISCOVERY REPORTS 



south of Wellington, New Zealand, the value previous to the phytoplankton outburst 

 was 51 mg., whilst at the northern boundary of the zone in the central part of the 

 South Pacific Ocean the value must be less than 38 mg. at this time. Values subsequent 

 to the phytoplankton outburst in the northern part of the zone are of the order of 

 30-40 mg. in the South Atlantic Ocean and considerably lower in the western part 

 of the South Pacific Ocean. 



Some small indication is shown of a secondary autumnal outburst of phytoplankton 

 on a small scale in this zone in May. 



In March 1934 in the sub-Antarctic zone south of the Falkland Islands (Sts. 1323- 

 1325), the surface content of silicate was less than 300 mg. In late September of the 

 same year and in the same position the surface content was 550-600 mg. at Sts. 1423- 

 1424. Just north of the Scotia Arc, north of the South Orkney Islands, two stations 

 (Sts. 1338 and 1435 respectively) taken immediately after those south of the Falklands 

 in March and September, gave surface values of less than 300 mg. in early April and 

 of 750 mg. in early October. 



In the third week of November 1933 the surface value south-west of Tristan da Cunha, 

 at the northern boundary of the sub-Antarctic zone was zero, but at St. 1196 in 

 48 15-6' S, 23 58-9' W, just north of the Antarctic convergence, the surface value 

 was 750 mg. 



In the eastern part of the South Atlantic Ocean in March 1933 a surface content at 

 St. 1 162 in 46 47-2' S, 12 39-4' E was 350 mg. South of Cape Town in March 1935 

 the surface content throughout the entire zone was less than 250 mg. at Sts. 1556-1558 

 (section 4, Plate VIII). In April 1932 at Sts. 848 and 849 (section 5, plate IX) between 

 Cape Town and Enderby Land, the sub- Antarctic surface water was 360 mg., a value 

 which very rapidly increased to one of 2400 mg. on crossing the convergence into 

 Antarctic surface water. North of Marion Island at St. 1565 in 44 047' S, 37 21-9' E 

 in mid-April 1935, the surface value was less than 250 mg.; the position of this station 

 was in the northern half of the zone. 



Between the Crozets and Durban (section 6, Plate XI) in the third week of May 1934 

 at Sts. 1 367-1 369, the surface content north of the Antarctic convergence was less than 

 300 mg. and zero south of the subtropical convergence. At St. 1553 in 49 35-1' S, 

 30 44-4' E, a position just north of the Antarctic convergence, the surface content in 

 early March 1935 was less than 250 mg. (section 4, Plate VIII). 



We have no silicate data for the sub-Antarctic Zone between about 40 E and the 

 area south of Australia, but in May 1932 along section 8 (Plate XIII) at Sts. 880-882 

 the sub- Antarctic water between Cape Leeuwin, Western Australia, and the ice-edge, 

 south of Australia in 63 41' S, 130 07' E, had a surface content which increased south- 

 wards across the zone from a value of 60 to one of 240 mg. 



South-east of New Zealand, towards the ice-edge north of the Ross Sea, we have two 

 sets of observations, one (section 12, Plate XVIII, Sts. 942-949), made in early September 

 1932 and the other (section 13, Plate XX, Sts. 1276 1280) in the third week of January 



