HORIZONTAL DISTRIBUTION, GROWTH AND DYNAMICS OF DISPERSAL 289 



that the scarcity of the krill we record in this great circumpolar belt is in fact a very real phenomenon 

 and not merely an appearance that could spring from inadequate sampling. I have not included in my 

 circumpolar coverage all the closely spaced stations we made round South Georgia^ and in the 

 Bransfield Strait (p. 51, Figs. 2 and 3), because this would have given a very exaggerated picture 

 of the density of our sampling between 60° and 30° W as compared for instance with that of Weddell 

 Middle and Weddell East, and of course of other sectors of the circumpolar sea. In both heavily 

 sampled regions I have limited the coverage figures to one station per month, thereby bringing the 

 overall oceanic coverage between 60° and 30° W more into line with that of other sectors. In the 

 result it will be seen the coverage figures, although based on a somewhat arbitrary northern limit, 

 will help the reader to decide at a glance to what extent the observed abundance, presence or absence 

 of the various stages of the whale food, from place to place, from month to month or from season to 

 season, could be said to be real or to what extent it might be questioned on the ground that whereas 

 in some areas sampling was heavy in others it was negligible or absent. 



To avoid interference with the mass of other plotted detail, much of which is often very crowded, 

 the distributional charts are without annotation throughout. For all place-names, hydrological 

 boundaries and other physical features mentioned in the text, however, the reader is referred to 

 Fig. 4 on p. 58. 



It is important to note that, throughout the distributional charts, the monthly positions of the pack- 

 ice are mean positions so that except where instanced to the contrary stations which appear to lie well 

 inside it need not necessarily have done so. The vast majority of such stations would in fact have 

 been located at the ice-edge, if not outside it, at some greater or less distance away. 



Although the vast bulk of the data comes from Discovery Investigations sources, in the construction 

 of some of the horizontal and vertical series, but principally the latter, I have used additional data 

 based on material collected by the 'Norvegia' expeditions of 1927-8, 1929-30 and 1 930-1, by the 

 floating factory ' Vikingen ' in 1 929-30 and by the Australasian (B . A.N.Z. A.R.E.) expedition in 1 929-3 1 . 

 The Norwegian material was worked up by Rustad (1930 and 1934) and Ruud (1932), the results I am 

 glad to acknowledge, more especially the negative results, helping considerably to confirm and extend 

 my own findings on certain important aspects of the distributional problem. The Australian material, 

 which comes principally from the i-m. diameter stramin nets, was examined by Dr Keith Sheard 

 of the Commonwealth Scientific and Industrial Research Organisation whose records of the occur- 

 rence of the over 20 mm. or staple whale food class were kindly communicated to me. Again, as with 

 the Norwegian data, it is the negative rather than the positive results of this important expedition 

 that prove to be the most interesting. 



The eggs and larvae from the vertical samples 

 The eggs 



Taking the egg charts as a whole it cannot perhaps be too strongly emphasised, even at the cost of 

 repetition, that except for a single instance in December (Fig. 64) and for another two in February 

 (Fig. 65) our gatherings, contrary to all expectation in view of the vast scale (p. 211) on which the 

 krill must multiply, have throughout the spawning season repeatedly been exceedingly small, and for 

 this reason it must be acknowledged that in so far at least as the eggs are concerned the distributional 

 charts are not altogether satisfactory. They cannot, for instance, be said to carry the conviction of 

 those portraying the distribution of the larvae, which on the whole are based throughout on very 

 substantial samples. Clearly, except for the three instances mentioned above, the mass of the eggs 



1 For the local distribution of the krill on the South Georgia whaling grounds and the density of the seasonal sampling 

 there see pp. 417-20, Figs. 148-55. 



33 "« 



