254 
PLANT MARCHES. 
Nov., 1890. 
along the range of Scandinavian hills, before the shattered 
forces once again reached the Arctic Seas, and, for aught we 
know, may be still advancing towards the North Pole, for there 
is nothing to show that we have yet arrived at the anti-climax 
of the glacial age ; indeed, we may assume that it is within the 
bounds of possibility for Greenland to be again the earthly 
Paradise it has been—a rearrangement of land areas which 
would form a land-locked Arctic sea would certainly make 
that possible. 
It is not to be wondered at that botanists find a world of 
interest in these colonies of northern plants, left stranded 
upon the hills and mountains of far-off lands, severed entirely 
from each other, often separated by hundreds of miles without 
a single representative existing in the intervening space. 
Sometimes remarkable instances occur of the survival of 
single species in particular localities, such as on Dartmoor 
or the Peak of Derbyshire, in the forests of Germany or on 
the Harz mountains, all of which contribute evidence to the 
interesting story. Nor is the history nearly worked out yet. 
Diligent students throughout Europe and America are 
noting new information daily. In the Alps, Dr. Christ, Dr. 
Correvon, and Dr. Wolf are assiduously working, and their 
labours are throwing an entirely new light upon the subject. 
The latest reports from these eminent scholars declare that 
there are plant colonists settled in the Alps from the Hima¬ 
laya, from the Atlas Mountains, Siberia, Kamtscbatka, China, 
and Japan—from America North and South, New Zealand 
and Australia—from Turkestan, the Caucasus, Greece, the 
Carpathians, the Apennines, Dalmatia, Corsica and the Isles 
—from the Sierra Nevada and the Pyrenees, besides those 
known to inhabit Scandinavia and the North Seas. This 
indicates that either the glacial plant army of the North was 
more completely shattered and broken up than has been 
suspected, or there must have been other centres of plant 
creation of the same typical Alpine character, with climatic 
conditions permitting a transportation of species between 
countries lying far apart. 
In making out progressive development of vegetable life, 
and particularly of floral structures, much uncertainty must 
always exist as to the period of time when the earth was first 
adorned with briglit-petalled flowers. 
The Carboniferous measures enshrine the more elementarv 
form of cryptogamic vegetation, and the succeeding periods 
present us with evidence of advanced forms, but it was not 
until Cretaceous times that we discern the dawn of Dicotyle¬ 
donous plants, and even then the records of petalled flowers 
