Chap. XL 
DUEING THE GLACIAL PEKIOD. 
365 
(and it would be very difficult to prove this), received 
within the last few centuries, through occasional means 
of transport, immigrants from Europe or any other 
continent, that a poorly-stocked island, though standing 
more remote from the mainland, would not receive 
colonists by similar means. I do not doubt that out of 
twenty seeds or animals transported to an island, even 
if far less well-stocked than Britain, scarcely more than 
one would be so well fitted to its new home, as to 
become naturalised. But this, as it seems to me, is 
no valid argument against what would be effected by 
occasional means of transport, during the long lapse of 
geological time, whilst an island was being upheaved 
and formed, and before it had become fully stocked 
with inhabitants. On almost bare land, with few or no 
destructive insects or birds living there, nearly every 
seed, which chanced to arrive, if fitted for the climate, 
would be sure to germinate and survive. 
Dispersal during the Qlacial period ,—The identity of 
many plants and animals, on mountain-summits, sepa¬ 
rated from each other by hundreds of miles of low¬ 
lands, where the Alpine species could not possibly exist, 
is one of the most striking cases known of the same 
species living at distant points, without the apparent 
possibility of their having migrated from one to the 
other. It is indeed a remarkable fact to see so many 
of the same plants living on the snowy regions of the 
Alps or Pyrenees, and in the extreme northern parts 
of Europe; but it is far more remarkable, that the 
plants on the White Mountains, in the United States of 
America, are all the same with those of Labrador, and 
nearly all the same, as we hear from Asa Gray, with those 
on the loftiest mountains of Europe. Even as long ago 
as 1747, such facts led Gmelin to conclude that the 
