by this process.
Although the beaks and feet of birds are generally quite clean, I can
show that earth sometimes adheres to them: in one instance I removed
twenty-two grains of dry argillaceous earth from one foot of a
partridge, and in this earth there was a pebble quite as large as
the seed of a vetch. Thus seeds might occasionally be transported to
great distances; for many facts could be given showing that soil almost
everywhere is charged with seeds. Reflect for a moment on the millions
of quails which annually cross the Mediterranean; and can we doubt that
the earth adhering to their feet would sometimes include a few minute
seeds? But I shall presently have to recur to this subject.
As icebergs are known to be sometimes loaded with earth and stones, and
have even carried brushwood, bones, and the nest of a land-bird, I can
hardly doubt that they must occasionally have transported seeds from
one part to another of the arctic and antarctic regions, as suggested
by Lyell; and during the Glacial period from one part of the now
temperate regions to another. In the Azores, from the large number of
the species of plants common to Europe, in comparison with the plants
of other oceanic islands nearer to the mainland, and (as remarked by
Mr. H. C. Watson) from the somewhat northern character of the flora in
comparison with the latitude, I suspected that these islands had been
partly stocked by ice-borne seeds, during the Glacial epoch. At my
request Sir C. Lyell wrote to M. Hartung to inquire whether he had
observed erratic boulders on these islands, and he answered that he had
found large fragments of granite and other rocks, which do not occur in
the archipelago. Hence we may safely infer that icebergs formerly
landed their rocky burthens on the shores of these mid-ocean islands,
and it is at least possible that they may have brought thither the
seeds of northern plants.
Considering that the several above means of transport, and that several
other means, which without doubt remain to be discovered, have been in
action year after year, for centuries and tens of thousands of
years, it would I think be a marvellous fact if many plants had not
thus become widely transported. These means of transport are sometimes
called accidental, but this is not strictly correct: the currents of
the sea are not accidental, nor is the direction of prevalent gales of
wind. It should be observed that scarcely any means of transport would
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