294 DISCOVERY REPORTS 



5400 m. and the catch obtained, at Station 2594 in the last hour of the last day of February, consisted 

 of 3444 eggs presumed to be disposed in a 1500 m. water column as follows: 



Depth (m.) Eggs 



50-0 — 



100-50 — 



250-100 — 



500-250 — 



750-500 — 



1000-750 — 



1500-1000^ 3444 



Although the significance of this occurrence has been discussed on other pages (pp. 100, 184, 208-10), 

 for the convenience of the reader I shall review briefly the facts and the main points of the argument 

 presented there. The deep net at this station it will be recalled, fishing for some unknown part of its 

 course in the bottom water that comes from the west, must clearly have taken a substantial proportion, 

 if not all, of the eggs it captured from the cold deep stratum itself. It will be recalled, too, that a high 

 proportion, 75%, of the eggs obtained were in an advanced developmental phase, many apparently 

 about to hatch, if not actually on the point of, or in the process of, hatching. Three alternatives were 

 put forward to explain their presence in this deep situation: (i) they sank there from a spawning that 

 took place at a higher level, (2) they were there because the females sank or swam down there to 

 spawn, and (3) they got carried there from a distant spawning in the far western or south-western 

 reaches of the Weddell drift in the fast moving bottom water which in the neighbourhood of 

 Station 2594 appears to have upwelled to a point abnormally close to the surface. Of the three alter- 

 natives the first was considered the most likely and the third, in view of the immense distance involved, 

 the least likely or impossible. A point perhaps in favour of the second alternative is the fact that in 

 the same net there were nine adults (an exceptional number for a vertical net) which included three 

 spent females. There were, however, many adults including spent females at the surface and it is 

 possible that the deep open vertical net had sampled this population. While virtually rejecting the 

 third, however, it was pointed out that there might be other places where spawning was taking place 

 much closer at hand (within about 500 miles), in the shelf or slope waters for instance of the Coats 

 Land-Princess Martha Coast, near the very region in fact where Ross and later Bruce (p. 212) recorded 

 such violent interference with their bottom apparatus, from which the eggs could well have been 

 carried in the bottom water eastwards to 0° and even beyond. 



On reconsidering the whole matter there might yet it seems be a fourth alternative. Station 2594 

 although itself in very deep water lies little more than 1 20 miles north by west of the shallow but as 

 yet imperfectly delineated and sparsely sounded Maud Bank where the minimum depth so far recorded 

 (U.S.N. Hydrographic Office, 1955) is only 656 fathoms. If spawning takes place over this bank it is 

 conceivable that the eggs might get displaced obliquely away from it by the bottom water as it comes up 

 against it from the west. In support of this suggestion it might be noted that Deacon (1937, p. 109), 

 in his classic description of the bottom water, remarks that sudden changes in depth such as, for in- 

 stance, occur in the neighbourhood of submarine ridges like the Scotia Arc ' are certain to give rise 

 to turbulent movements in the bottom currents '. 



March-April. The captures of eggs for March-April (Fig. 66) are small or negligible and, such as 

 they are, are exclusively March records. While this may mean that spawning is now, that is in 

 March, on the wane, other considerations, based as before on the deep larval records, suggest that 



* It will be recalled (p. 100, note 2 and p. 184, Fig. 22) that this net did not close and fished open to the surface. The 

 absence of eggs at all levels above 1000 m. and the advanced developmental condition of the eggs in the deep open net 

 suggest strongly, however, that they did, or the vast majority of them did, come from below 1000 m. See also p. 183, Fig. 21. 



