| Considering that
several
means of transport, and that
other means, which without doubt remain to be discovered, have been in action year after
for
tens of thousands of years, it
I
be a marvellous fact if many plants had not thus become widely transported. These means of transport are
called accidental, but this is not strictly correct: the currents of the sea are not
nor is the direction of prevalent gales of wind. It should be observed that scarcely any means of transport would carry seeds for very great
for seeds do not retain their vitality when exposed for a great length of time to the action of sea-water; nor could they be long carried in the crops or intestines of birds. These means, however, would suffice for occasional transport across tracts of sea some hundred miles in breadth, or from island to island, or from a continent to a neighbouring island, but not from one distant continent to another. The floras of distant continents would not by such means become
→in any great degree;
but would remain as distinct as
now
→see them to be. The currents, from their course, would never bring seeds from North America to Britain, though they might and do bring seeds from the West Indies to our western shores, where, if not killed by
→so long an
immersion in
they could not endure our climate. Almost every year, one or two land-birds are blown across the whole Atlantic Ocean, from North America to the western shores of Ireland and England; but seeds could be transported by these
only by one means, namely,
dirt
to their
→which
is in itself a rare accident. Even in this case, how
|
