134 ME. C. DARWIN OS THE ACTION OF SEA- WATER 



was killed by 25 days' immersion ; three of the Crueiferce survived 

 85 days : this power of endurance in the seeds of this family is, 

 perhaps, surprising, considering the oil in their seeds. Nine 

 Leguminosce were tried; these all resisted the salt water badly, 

 with the exception of the hard thin seeds of Mimosa sensitiva, 

 which germinated pretty well after 50 days; three species of 

 Lupine seemed just able occasionally to withstand about 36 days' 

 immersion ; the seeds of the other Leguminosce having all been 

 killed by much shorter periods. I suspect that it is the water, 

 and not the salt, which kills the Leguminosce ; at least I found that 

 a lot of fresh " Thurston Reliance" peas were all killed by 13 days' 

 immersion in pure water* ; and I have been assured that a much 

 shorter immersion will kill kidney beans. Lastly, seven species 

 of the allied families of Hydrophyllacece and Polemoniacece (six 

 having been selected by Mr. Berkeley) were killed by a month's 

 immersion, and so great a proportion can hardly be accidental. 



From the great difference in the powers of resistance to the 

 sea-water in the different families just specified, and even in the 

 varieties of the same species ; and from the Leguminosce being 

 apparently in this respect the tenderest, whereas they aro 

 generally believed to keep longer than any other seeds in a dry 

 state, I think we may learn a lesson of caution, not to infer 

 with too much certainty which seeds will endure longest when 

 naturally buried in damp earth, from knowing what kinds will 

 keep best in an artificial state. 



I had intended trying many more seeds, as I at one time 

 thought that these experiments would have thrown more light on 

 the dispersal of plants than I now think they do. I soon became 

 aware that most seeds, in accordance with the common experience 

 of gardeners, sink in water ; at least I have found this to be the 

 case, after a few days, with the 51 kinds of seeds which I have 

 myself tried; so that such seeds could not possibly be trans- 

 ported by sea-currents beyond a very short distance. Some few 

 seeds, however, do float, as I have tried with some of those cast 

 by the Gulf Stream on the coast of Norway. From knowing that 

 timber is often cast on the shores of oceanic islands far from the 

 mainland, and from having met with accounts of floating vege- 



* Loiseleur-Deslongchamps says (Consid. sur les Cereales, Part ii. p. 234) 

 that in wheat put into water the embryo comes out in the course of two days j 

 as Mr. Berkeley's wheat survived after 30 days' immersion in sea-water, one 

 may suspect that in this case, the seed would survive longer under sea- water 

 than under fresh water. 



