384 MEANS OF DISPERSAL, 



sea-Tvater. The majority sunk quickly, but some whicli, 

 while green, floated, for a very short time, when dried, 

 floated much longer; for instance, ripe hazel-nuts sunk 

 immediately, but when dried they floated for ninety days, 

 and afterward 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 after- 

 ward germinated; the ripe seeds of Helosciadium sunk in 

 two days, when dried they floated for above ninety days, 

 and afterward 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 |4 kinds of seeds germinated after an 

 immersion of twenty-eight days; and as -^f distinct species 

 with ripe fruit (but not all the same species as in the forego- 

 ing 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 -^-^-^ 

 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 -^ 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 favorable spot, would germinate. 



Subsequently to my experiments, M. Martens tried sim- 

 ilar ones, but in a much better manner, for he placed the 

 seeds in a box in the actual sea, so that they were alter- 

 nately wet and exposed to the air like really floating 

 plants. He tried ninety-eight seeds, mostly difl'erent from 

 mine, but he chose many large fruits, and likewise seeds, 

 from plants which live near the sea; and this would have 

 favored 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 -^f of his seeds of different kinds 

 floated for forty-two days, and were then capable of ger- 

 mination. But I do not doubt that plants exposed to the 



