360 
GEOGEAPHICAL DISTEIBUTION. 
Chap. XI 
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 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 flota¬ 
tion 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 of his 
seeds floated for 42 days, and were then capable of ger¬ 
mination. But I do not doubt that plants exposed to 
the waves would float for a less time than those pro¬ 
tected from violent movement as in our experiments. 
Therefore it would perhaps be safer to assume that the 
seeds of about 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 in¬ 
teresting; 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, 
