282 THE VOYAGE OF H.M.S. CHALLENGER. 



days ; when dried they floated more than ninety days, and afterwards germinated. He 

 also alludes to another way in which the sea might indirectly assist in the dispersion of 

 plants. 1 "But seeds may be occasionally transported in another manner. Drift timber 

 is thrown up on most islands, even on those in the midst of the widest oceans ; and the 

 natives of the coral islands in the Pacific procure stones for their tools solely from the 

 roots of drifted trees. I find, on examination, that when irregularly -shaped stones are 

 embedded in the roots of trees, small parcels of earth are frequently enclosed in their 

 interstices and behind them — so perfectly, that not a particle could be washed away in the 

 longest transport : out of one small portion of earth thus completely enclosed by wood in 

 an oak about fifty years old, three dicotyledonous plants germinated. I am certain of the 

 accuracy of this observation. Again, I can show that the carcases of birds, when floating 

 on the sea, sometimes escape being immediately devoured ; and seeds of many kinds in the 

 crops of floating birds long retain their vitality. Peas and vetches, for instance, are 

 killed by even a few days' immersion in sea-water ; but some taken out of the crop of a 

 pigeon which had floated on artificial salt water for thirty days, to my surprise, nearly all 

 germinated." 



Two years later Professor Ch. Martins, of Montpellier, published 2 an account of some 

 similar experiments tried by him with mostly different kinds of seeds. He first of all 

 noted which of them floated in sea- water ; but it is not clear whether the trial was merely 

 momentary or prolonged. However, of ninety-eight kinds of seeds and seed-vessels con- 

 taining seeds, fifty-nine, we are informed, floated. Instead of plunging them in water, as 

 Darwin and Berkeley did, Martins employed a perforated box, with as many compartments 

 as kinds of seeds, and attached it to a buoy, so that it rose and fell with the waves, and 

 the seeds were thus alternately exposed to the air and water, as they would be if floating 

 free. After forty-five days' exposure the box was opened, when it was found that forty- 

 one kinds of seed out of ninety-eight were rotten. The remaining fifty-seven apparently 

 sound ones were sown, and of these thirty-five germinated ; but as sixteen of them were 

 of greater specific gravity than sea-water, they would have to be deducted, leaving only 

 nineteen species out of ninety-eight that might possibly germinate and establish them- 

 selves on a coast after floating for six weeks on the surface of the sea. These nineteen 

 species were : Asclepias cornuti, Asphodelus cerasiferus, Beta vulgaris, Cakile maritime/,, 

 Cucurbita pepo, Ephedra distachija, Eryngiwm maritimum, Euphorbia paralias, Gingko 

 biloba, Linum maritimum, Nelumbium speciosum, Paliurus aculeatus, Pancratium mari- 

 iiinnm, Ricinus africanus, Ricinus communis? Rumex aquaticus, Salsola kali, Scabiosa 

 tnaritima, and Xanihium macrocarpum. 



About half of the species, it will be seen, are essentially littoral plants, whose seeds 

 are ordinarily exposed to the influence of sea- water. 



1 Loc. cit., p. 360. - Bulletin de la Societe" Lolanique de France, iii. p. 324. 



Really varieties of one species. 



