Chap. XI. MEANS OF DISPEESAL. 359 



For convenience sake I chiefly tried small seeds, 

 without the capsule or fruit ; and as all of these sank 

 in a few days, they could not be floated across wide 

 spaces of the sea, whether or not they were injured by 

 the salt-water. Afterwards I tried some larger fruits, 

 capsides, &c, and some of these floated for a long- 

 time. It is well known what a difference there is in the 

 buoyancy of green and seasoned timber ; and it occurred 

 to me that floods might wash down plants or branches, 

 and that these might be dried on the banks, and then 

 by a fresh rise in the stream be washed into the sea. 

 Hence I was led to dry stems and 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 they germinated ; an asparagus plant 

 with ripe berries floated for 23 days, when dried it 

 floated for 85 days, and the seeds afterwards germi- 

 nated : the ripe seeds of Helosciadiuni sank in two days, 

 when dried they floated for above 90 days, and after- 

 wards 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 f^ 

 seeds germinated after an immersion of 28 days ; and 

 as i| plants with ripe fruit (but not all the same species 

 as in the foregoing experiment) floated, after being dried, 

 for above 28 days, as far as we may infer anything from 

 these scanty facts, we may conclude that the seeds of 

 j 1 ^ plants of any country might be floated by sea-cur- 

 rents during 28 days, and would retain their power of 

 germination. In Johnston's Physical Atlas, the average 

 rate of the several Atlantic currents is 33 miles per 

 diem (some currents running at the rate of CO miles 



