consisting of mere piles of volcanic matter.

I must now say a few words on what are called accidental means, but
which more properly might be called occasional means of distribution.
I shall here confine myself to plants. In botanical works, this or
that plant is stated to be ill adapted for wide dissemination; but for
transport across the sea, the greater or less facilities may be said to
be almost wholly unknown. Until I tried, with Mr. Berkeley's aid, a
few experiments, it was not even known how far seeds could resist the
injurious action of sea-water. To my surprise I found that out of 87
kinds, 64 germinated after an immersion of 28 days, and a few survived
an immersion of 137 days. For convenience sake I chiefly tried small
seeds, without the capsule or fruit; and as all of these sank in a few
days, they could not be floated across wide spaces of the sea, whether
or not they were injured by the salt-water. Afterwards I tried some
larger fruits, capsules, etc., and some of these floated for a long
time. It is well known what a difference there is in the buoyancy of
green and seasoned timber; and it occurred to me that floods might wash
down plants or branches, and that these might be dried on the banks, and
then by a fresh rise in the stream be washed into the sea. Hence I was
led to dry stems and branches of 94 plants with ripe fruit, and to place
them on sea water. The majority sank quickly, but some which whilst
green floated for a very short time, when dried floated much longer; for
instance, ripe hazel-nuts sank immediately, but when dried, they floated
for 90 days and afterwards when planted they germinated; an asparagus
plant with ripe berries floated for 23 days, when dried it floated
for 85 days, and the seeds afterwards germinated: the ripe seeds of
Helosciadium sank in two days, when dried they floated for above 90
days, and afterwards germinated. Altogether out of the 94 dried plants,
18 floated for above 28 days, and some of the 18 floated for a very much
longer period. So that as 64/87 seeds germinated after an immersion
of 28 days; and as 18/94 plants with ripe fruit (but not all the same
species as in the foregoing experiment) floated, after being dried, for
above 28 days, as far as we may infer anything from these scanty facts,
we may conclude that the seeds of 14/100 plants of any country might be
floated by sea-currents during 28 days, and would retain their power
of germination. In Johnston's