d 
324 ORIGIN OF THE 
and, lastly, most of the English reptiles are wanting in Ireland. 
These considerations seem not to militate against the theory of the 
same plants having originated in several places simultaneously, since, 
as we have noticed before, leafless and flowerless plants of the 
same species are more frequently found in far distant countries, than 
is the case with the more perfect plants; and on the other hand, we 
are justified in assuming that the most perfect animals have rarely, if 
ever, been produced originally in more than one locality. 
Some detailed instances may serve to place this matter in a clearer 
light. Professor Forbes, a celebrated English author, in treating of 
this subject, and proceeding on the theory of one parent plant, en- 
deavours to explain the manner in which the British Islands have 
derived their existing flora. The presence of some Spanish plants in 
the west of Ireland leads him to suppose that there once existed 
a large continent, which not only oceupied the area now covered 
by the Spanish Sea, but extended to the Azores, and even beyond, 
into the Atlantic. Those plants that are common to the South of 
France on the one side, and on the other to the south of Ireland 
and the south-west of England, have migrated at the time when 
no channel existed; while the alpine (polar) plants, common to the 
mountains of Scotland, Westmoreland, and Wales, and to those 
of Scandinavia, immigrated from the north, at a period when the 
coast climate equalled in severity that of the tops of mountains. 
Migration is conjectured to have taken place by means of frozen 
islands, or else of some great northern continent, subsequently sub- 
merged, between Scotland, Scandinavia, and Iceland. Finally, it is 
supposed that, in more recent times, the bottom of the North Sea 
has been raised, connecting England with Denmark and Germany, 
whereby the plants immigrating from the latter country have forced 
those of Scandinavia into the Scottish Highlands on the right hand, 
. some few having found shelter in Wales, Cumberland, and Westmore- 
land; expelling on the left side the southern vegetable forms, and thus 
occupying the greater proportion of the territory.* According to our 
author, the Polar flora bordered originally on the Mediterranean flora ; 
a theory which is opposed to all analogy derived from the present enit 
.. ef things. 
* This connection once established, would seem to favour equally much the migra- 
tion of English plants into Germany. 
