hem 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 Physical
Atlas, the average {360} rate of the several Atlantic currents is 33 miles
per diem (some currents running at the rate of 60 miles per diem); on this
average, the seeds of 14/100 plants belonging to one country might be
floated across 924 miles of sea to another country; and when stranded, if
blown to a favourable spot by an inland gale, they would germinate.

Subsequently to my experiments, M. Martens tried similar ones, but in a
much better manner, for he placed the seeds in a box in the actual sea, so
that they were alternately wet and exposed to the air like really floating
plants. He tried 98 seeds, mostly different from mine; but he chose many
large fruits and likewise seeds from plants which live near the sea; and
this would have favoured the average length of their flotation and of their
resistance to the injurious action of the salt-water. On the other hand he
did not previously dry the plants or branches with the fruit; and this, as
we have seen, would have caused some of them to have floated much longer.
The result was that 18/98 of his seeds floated for 42 days, and were then
capable of germination. But I do not doubt that plants exposed to the waves
would float for a less time than those protected from violent movement as
in our experiments. Therefore it would perhaps be safer to assume that the
seeds of about 10/100 plants of a flora, af