Physical Atlas, the average 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, after having been dried, could be floated
across a space of sea 900 miles in width, and would then germinate.
The fact of the larger fruits often floating longer than the small,
is interesting; as plants with large seeds or fruit could hardly be
transported by any other means; and Alph. de Candolle has shown that
such plants generally have restricted ranges.

But seeds may be occasionally transported in another manner. Drift
timber is thrown up on most islands, even on those in the midst of the
widest oceans; and the natives of the coral-islands in the Pacific,
procure stones for their tools, solely from the roots of drifted trees,
these stones being a valuable royal tax. I find on examination, that
when irregularly shaped stones are embedded in the roots of trees, small
parcels of earth are very frequently enclosed in their interstices and
behind them,--so perfectly that not a particle could be washed away in
the longest transport: out of one small portion of earth thus COMPLETELY
enclosed by wood in an oak about 50 years old, three dicotyledonous
plants germinated: I am