er the microscope
several seeds, and raised from them seven grass plants, belonging to
two species, of two genera. Hence a swarm of locusts, such as that which
visited Madeira, might readily be the means of introducing several kinds
of plants into an island lying far from the mainland.

Although the beaks and feet of birds are generally clean, earth
sometimes adheres to them: in one case I removed sixty-one grains, and
in another case twenty-two grains of dry argillaceous earth from the
foot of a partridge, and in the earth there was a pebble as large as the
seed of a vetch. Here is a better case: the leg of a woodcock was sent
to me by a friend, with a little cake of dry earth attached to the
shank, weighing only nine grains; and this contained a seed of
the toad-rush (Juncus bufonius) which germinated and flowered. Mr.
Swaysland, of Brighton, who during the last forty years has paid close
attention to our migratory birds, informs me that he has often shot
wagtails (Motacillae), wheatears, and whinchats (Saxicolae), on their
first arrival on our shores, before they had alighted; and he has
several times noticed little cakes of earth attached to their feet. Many
facts could be given showing how generally soil is charged with seeds.
For instance, Professor Newton sent me the leg of a red-legged partridge
(Caccabis rufa) which had been wounded and could not fly, with a ball of
hard earth adhering to it, and weighing six and a half ounces. The earth
had been kept for three years, but when broken, watered and placed
under a bell glass, no less than eighty-two plants sprung from it: these
consisted of twelve monocotyledons, including the common oat, and at
least one kind of grass, and of seventy dicotyledons, which consisted,
judging from the young leaves, of at least three distinct species.
With such facts before us, can we doubt that the many birds which are
annually blown by gales across great spaces of ocean, and which
annually migrate--for instance, the millions of quails across the
Mediterranean--must occasionally transport a few seeds embedded in
dirt adhering to their feet or beaks? But I shall 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, it can
hardly be doubted that they must occasionally, as suggested by Lyell,
have transported seeds from one part to another of the arctic and
antarctic regi