DESCRIPTION OF THE ISLANDS 369 



laminae are twenty-four feet in length. The South Orkneys fragment was later 

 assigned to a separate species, L. simidans. Similar plants were discovered at South 

 Georgia and Graham Land by Skottsberg,^ who assigned them to a new genus, Phvllo- 

 gigas, and believing them to be identical with the South Orkneys-Victoria Land 

 specimens united all as a single species, P. graiidifolius. Although Skottsberg's generic 

 name has now been adopted for the South Orkney fragment in the Marine Algae of the 

 Scottish National Antarctic Expedition, it is still regarded there as a separate species, 

 P. simidans. Thus although no actual Macrocystis pyrifera has been described from the 

 South Orkneys there can be little doubt that a large weed superficially resembling kelp 

 exists in the neighbourhood of the group, but there seems to be considerable divergence 

 of opinion as to what it actually may be. Clearly it is not abundant, or is at any rate 

 rarely seen at the surface, so that it can be disregarded altogether as an aid to navigation. 

 The Lessonia grandifolia from Cape Adare was brought up on an anchor in eighteen 

 fathoms of water. It is characterized by the great length of its laminae, and, in contrast 

 to the long and powerful stems of Macrocystis pyrifera, by the extreme shortness and 

 comparative weakness of its stems, which except in very shallow water are quite in- 

 capable of bearing the laminae to the surface despite their abnormal length. If this, 

 then, is the plant which grows at the South Orkneys, it is evident that its habitat is the 

 sea bed where the water is fairly deep, and that it can scarcely ever appear at the surface 

 except when torn from the bottom by icebergs or by storms of exceptional violence. 



It has often been stated that the absence of kelp and other large sea-weeds from the 

 littoral and sublittoral zones of high southern latitudes is due to the grinding action of 

 pack-ice as it works against the land, and if this be true it is highly improbable that 

 any could exist at the South Orkneys, which are subject to complete envelopment by 

 pack-ice for a longer or shorter period every year. Moreover, if kelp is absent from the 

 South Shetlands, as it appears to be, it is all the more likely to be absent from the South 

 Orkneys which on the whole are liable to severer ice action than the South Shetlands. 

 And yet, as Kemp suggests,'- there may be other reasons for the absence of kelp from 

 these regions ; for although pack-ice would no doubt completely destroy the plants that 

 might grow between tide marks or in the very shallow water adjoining, it could not, 

 unless it were rising and falling on a heavy swell, destroy any but the distal laminae of 

 those that might be anchored in the deeper water beyond. Indeed, it is not incon- 

 ceivable that in very calm conditions pack might pass over offshore kelp without doing 

 it any great harm, although conversely much no doubt would be destroyed if the weather 

 were very rough. It would seem, then, that ice need not bring about the total destruc- 

 tion of kelp that it is said to do, and that if other conditions were favourable to its 

 growth some at least must escape. As we saw for ourselves in January 1933 other algae 

 very much smaller and more fragile than kelp contrive with a considerable measure 

 of success to maintain a footing in the littoral zone in places where they are unlikely to 



' Skottsberg, C, 1907, Zur Kemitnis der subantarktischen imd antartttischen Meeresalgen. I. Phaeophyceen, 

 Schwedische Siidpolar-Expedition, 1901-3, iv, No. 6, pp. 63-9. 

 - Kemp, S., and Nelson, A. L., 1931, loc. cit., p. 158. 



