490 SECTIONAL TRANSACTIONS.—D. 
current receives additions from the westerly near South Georgia and near 
the Kerguelen-Gaussberg ridge; mixing of antarctic and sub-antarctic 
water takes place across the Antarctic Convergence between the Falkland 
Islands and South Georgia. 
Mr. Ditwyn Joun.—Plankion. 
The different surface waters of the southern hemisphere have distinctive 
planktonic faunas. The recent work of the R.R.S. Discovery IT has led to 
an extensive knowledge of those of the antarctic and sub-antarctic surface 
waters ; series of tow-nettings were made across each kind of water in all 
sectors of the hemisphere and at all seasons of the year. The boundary 
which separates them, the Antarctic Convergence, acts as a hard and fast 
barrier to the horizontal distribution of certain groups of animals though 
not to others. 
Two species of Euphausia occur only in the antarctic, four only in the sub- 
antarctic : there is one species, an exception, which occurs in both. ‘Two 
Chaetognaths, species of different genera, occur very numerously throughout 
the surface waters of the antarctic and sub-antarctic, but in both species 
there are two ‘ races,’ one confined to each kind of water. Few Copepoda 
are limited in their horizontal distribution by the Antarctic Convergence. 
In some places where there is a bend in the convergence and abnormal 
hydrological conditions occur, areas of mixed antarctic and sub-antarctic 
plankton are found. The extent to which the power of vertical migration 
is involved in this horizontal mixing is discussed. 
The surface current of antarctic water flowing to the west, south of 65° S., 
has planktonic forms peculiar to itself. They are carried north, even to the 
convergence, where the configuration of antarctic land deflects this water 
northwards. The most interesting and important example is the wide 
distribution of whale-food, Euphausia superba, in the sector of the antarctic 
which is affected by the Weddell Sea current. 
Mr. F. S. RussELL.—The behaviour of marine plankton animals in 
relation to the conditions of their surroundings and to their life- 
cycles (3.15). 
Mr, P. ULLYott.—Vertical movements of the Zooplankton (3.45). 
Saturday, September 9. 
Excursion to Charnwood Forest. Leader: Mr. W. E. Mayes. 
Monday, September 11. 
Mr. L. C. BEADLE.—Osmotic regulation in Gunda ulve (10.0). 
Dr. Stewart MacLacan.—The prediction of insect outbreaks in Britain 
(10.30). 
Discussion on The structure of protoplasm (Mr. J. E. Harris; Dr. D. 
Jorpan Lioyp; Mr. W. T. AstBury) (11.0). ce 
