The universal geography : earth and its inhabitants

PLOEA. 23
without being inconvenienced to the same extent as would Bretons or Provencals
under similar circumstances. On the other hand, foreigners born under brighter
skies generally complain about the paleness of the sun, and of the fogs, which in
some of the towns, where they are impregnated with the smoke rising from thou-
sands of chimneys, are very dense, and hinder the free circulation of the air.
Flora.
In its main features the British flora resembles that of Continental Europe, with
a strong intermingling of American species, increasing in number as we travel
towards the west. There are only a few plants not indigenous to Continental
Europe, of which the most remarkable is the jointed pipewort, or Erioeaulon
septanguJarc, a native of tropical America, found in the Isle of Skj'e and in the
west of Ireland, whither the gulf- stream has carried it.
The researches of botanists have clearly established the fact that the existing
flora is the outcome of successive floral invasions which transpired during the
tertiary age, whilst the British Islands still formed a part of the neighbouring
continent. The first of these invasions of surviving species took place probably in
the eocene age, and is confined to the hilly parts of South-western Ireland. It is
an alpine flora, quite distinct from the flora of the Scotch and "Welsh mountains,
and has been traced to the Western Pyrenees. A second botanical province
embraces Devonshire and Cornwall, South "Wales, and a considerable portion of
Southern Ireland. When this flora first obtained a footing upon the British Isles a
barrier must have stretched across what is now the English Channel to Brittany and
Xormandy. Some of its most characteristic species are the beautiful ciliated heath,
the purple spurge, and the graceful Sibthorpia. A third invasion took place when
England was joined to the north of France. This flora is more especially deve-
loped in the chalk districts of South-eastern England. To this succeeded, during
the glacial period, an invasion of alpine plants, principally from Norway, which
survive on the hills of "Wales, Northern England, and Scotland. "When the
glaciers finally melted away, and the land emerged anew, there occurred the
fifth invasion, the last in order of time, but the most important in its influence on
the character of British vegetation. This invasion emanated from Germany, at
that period joined to the British Isles by a wide plain stretching across the southern
portion of the North Sea. This hardy flora rapidly spread over the country,
where it found a congenial soil ; it invaded Scotland and Ireland, mingled with
the floras of more ancient date, and pushed them back to the west and south-west.
Though Europe has plaj-ed the principal part in giving to the British Isles
their vegetable clothing, America, too, has contributed a share ; but whilst the
European species migrated by land, those of American origin were carried to these
shores, as to the coast of Norway, through the agency of the gulf-stream, and
hence they are most numerous on the Hebrides, the Orkneys, and the Shetland
Islands, where they outnumber European species.
Climate has exercised a paramount influence upon the distribution of British