MEANS OF DISPERSAL. 385 



waves would float for a less time than those protected from, 

 violent movement as in our experiments. Therefore, it 

 would perhaps be safer to assume that the seeds of about 

 tW plants of a flora, after having been dried, could be 

 floated across a space of sea 900 miles in width, and would 

 then germinate. The facts of the larger fruits often float- 

 ing longer than the small, is interesting; as plants with 

 large seeds or fruit which, as Alph. de Candolle has shown, 

 generally have restricted ranges, could hardly be trans- 

 ported by any other means. 



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, these 

 stones being a valuable royal tax. I find that when irregu- 

 larly shaped stones are embedded in the roots of trees, 

 small parcels of earth are frequently inclosed in their inter- 

 stices and behind them, so perfectly that not a particle 

 could be washed away during the longest transport: out of 

 one small portion of earth thus completely inclosed by the 

 roots of 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 carcasses of birds, 

 when floating on the sea, sometimes escape being immedi- 

 ately devoured: and many kinds of seeds 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 sea-water for thirty days, to 

 my surprise nearly all germinated. 



Living birds can hardly fail to be highly eiiective agents 

 in the transportation of seeds. I could give many facts 

 showing how frequently birds of many kinds are blown by 

 gales to vast distances across the ocean. We may safely 

 assume that u-nder such circumstances their rate of flight 

 would often be thirty-five miles an hour; and some authors 

 have given a far higher estimate. I have never seen an 

 instance of nutritious seeds passing through the intestines 

 of a bird; but hard seeds of fruit pass uninjured through 

 even the digestive organs of a turkey. In the course of 

 two months, I picked up in my garden twelve kinds of 



