434 
ORIGIN OF LIFE IN AMERICA 
insects from the antarctic regions, Dr. Enderlein comes to 
the conclusion that the existing features of distribution are 
best explained by means of Dr. Simroth’s pendulation theory. 
That theory is founded on the supposed pendulation or shifting 
of the poles in the course of time. As the South Pole gradu¬ 
ally travelled northward, the present antarctic regions would 
have slowly moved into more favourable climatic regions, and 
have thus become habitable for such temperate animals and 
plants as were able to reach them. When the Pole once more 
moved back towards its present position, the antarctic fauna 
and flora would again have endeavoured to regain suitable 
climatic regions by any other land connections then available. 
In this manner it is perfectly conceivable how, by a combina¬ 
tion of serviceable land connections and a shifting Pole, the 
present geographical distribution of the animals and plants 
alluded to could have been brought about. We need not 
imagine the former existence of a huge continent from which 
long peninsulae projected, simultaneously joining all the 
southern continents with one another. More slender land 
bridges uniting one continent after another during succes¬ 
sive geological ages with an antarctic land-mass would be 
sufficient. Dr. Enderlein supposes that probably towards the 
end of Cretaceous or in Eocene times the antarctic “ Heard- 
Marion,” area was connected by land with Madagascar and 
indirectly with South Africa. Tierra del Fuego extended 
beyond the Falkland islands, South Georgia, South Orkneys 
and Shetlands to Antarctica about the same time, and also, 
perhaps during the Oligocene and Miocene Periods. Australia 
was joined to the same area in Oligocene or Miocene times. 
Dr. Enderlein,* on the other hand, believes New Zealand to 
have been completely isolated from all other regions since the 
Eocene Period. 
The theory appears simple and plausible, and if it should be 
proved that the Poles shift their position to the extent assumed 
by Professor Simroth, it would explain the causes of some of 
the great movements of animal life in a satisfactory manner. 
Nevertheless, we cannot, as Dr. Enderlein acknowledges, dis- 
* Enderlein, Gunther, “ Biologische Bedeutung der Antarktis,” 
pp. 333 — 350. 
