Chap. XII.] MEANS OF DISPERSAL. 143 



of 137 days. It deserves notice that certain orders were 

 far more injured than others : nine Leguminosse were 

 tried, and, with one exception, they resisted the salt-water 

 badly; seven species of the allied orders, Hydrophyllacese 

 and Polemoniacese, were all killed by a month's im- 

 mersion. 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 have been floated 

 across wide spaces of the sea, whether or not they were 

 injured by the salt-water. Afterwards I tried some larger 

 fruits, capsules, &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 would often wash into the sea dried 

 plants or branches with seed-capsules or fruit attached 

 to them. Hence I was led to dry the 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 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 Helosciadium 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 f f kinds of 

 seeds germinated after an immersion of 28 days ; and as 

 ^1 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 



