hey floated for ninety days, and afterwards when planted germinated;
an asparagus plant with ripe berries floated for twenty-three days,
when dried it floated for eighty-five days, and the seeds afterwards
germinated: the ripe seeds of Helosciadium sank in two days, when
dried they floated for above ninety days, and afterwards germinated.
Altogether, out of the ninety-four dried plants, eighteen floated for
above twenty-eight days; and some of the eighteen floated for a very
much longer period. So that as 64/87 kinds of seeds germinated after an
immersion of twenty-eight days; and as 18/94 distinct species with ripe
fruit (but not all the same species as in the foregoing experiment)
floated, after being dried, for above twenty-eight days, we may
conclude, as far as anything can be inferred from these scanty facts,
that the seeds of 14/100 kinds of plants of any country might be floated
by sea-currents during twenty-eight days, and would retain their power
of germination. In Johnston's Physical Atlas, the average rate of the
several Atlantic currents is thirty-three miles per diem (some currents
running at the rate of sixty 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 by an
inland gale to a favourable spot, 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 ninety-eight 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 both the average
length of their flotation and 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 of different kinds floated for forty-two 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, after
having been dried, could be floate