364 POLAR PROBLEMS 



during only a few days of the summer, when solar radiation may be 

 very high, with a correlated rapidity of growth and reproduction. 

 Plants, as Darwin has said, exist not where they can, but only where 

 they must, and the wonder is, in view of the unparalleled severity of 

 the environment, the absence of any warm period, and the presence 

 of vast numbers of penguins, which, as Rudmose Brown^"* has shown, 

 render much of the bare surface unsuitable for vegetation, that post- 

 glacial plants have contrived to gain even the slight foothold to which 

 they now cling. 



Skottsberg considers the plant life of Palmer Land (by some called 

 Graham Land), the South Shetlands, and South Orkneys as essentially 

 Antarctic. The sub-Antarctic vegetation which occurs on most of the 

 other surrounding islands, in part north of the tree limit at Gough and 

 Amsterdam Islands, offers a marked contrast with the truly polar flora. 

 While the vascular plants are still relatively limited, we do find local 

 species of widely distributed northern genera, such as Carex, Poa, and 

 Ranunculus, together with Alpine types of south temperate genera. 

 The " Kerguelen cabbage " {Pringlea antiscorhutica) has no near relative 

 in the southern hemisphere but is closely related to the northern 

 Cochlearia. 



As Skottsberg^^ lists the vegetation of South Georgia, a typically 

 sub- Antarctic island, it comprises 214 species, of which 19 are vascular 

 plants, 99 mosses, 36 hepatics, and 58 lichens. Spitsbergen, which 

 extends to latitude 80° N., has 120 species of vascular plants. The 

 most conspicuous and generally distributed element in the South 

 Georgian flora is the tussock grass {Poa flahellata) , which is found at 

 nearly every southern island. Macquarie Island, on about the same 

 parallel as South Georgia, has 34 vascular plants. 



INSECTS 



On the Antarctic Continent there is almost no land fauna away 

 from the penguin rookeries, in the vicinity of which are found mites, 

 such lowly organized insects as Collembola, and a wingless Chironomid 

 fly, together with a few rotifers, a tardigrade (well named Macrohiotus 

 antarcticus), and two or three protozoans in the moss. Members of 

 several of these groups, like the vegetation, are characterized by 

 enormously specialized viability. They awaken for at most a few days 

 in summer in order to carry on their active life processes, and they 

 are capable of existing for months, perhaps for years, in a frozen 



25 R. N. Rudmose Brown: The Life and Habits of Penguins (Scottish National Antarctic Expedi- 

 tion: Report on the Scientific Results of the Voyage of S. Y. "Scotia" . . . 1902-1904. under the 

 leadership of W. S. Bruce, Vol. 4: Zoology, pp. 249-253), Edinburgh, 1915. 



2^ Carl Skottsberg: Die Gefasspflanzen Siidgeorgiens (Wissenschaftliche Ergebnisse der Schwed- 

 ischen Sudpolar-Expedition 1901-1903, herausg. von Otto Nordenskjold, Vol. 4, Part III, pp. 1-12), 

 Stockholm, 1905. 



