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 



