Page - 406 - in The Origin of Species

406 ORIGIN OF SPECIES 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 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 Helosci- adium 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 |^ kinds of seeds germinated after an immersion of 28 days; and as -^f distinct species with ripe fruit (but not all the same species as in the foregoing experiment) floated, after being dried, for above 28 days, we may conclude, as far as anything can be inferred from these scanty facts, that the seeds of -^^-^ kinds of plants of any country might be floated by sea-cur- rents during 28 days, and would retain their power of ger- mination. In Johnston's Physical Atlas, the average rate of the several Atlantic currents is 33 miles per diem (some cur- rents 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 by an inland gale to a favour- able 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 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 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 pre- viously 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 -^f of his seeds of different kinds floated for 42 days, and were then capable of germination. But I do not doubt that plants exposed to the