In comparatively few years a small island in mid ocean had quite an important addition to its flora, merely from the fact that the grave of an officer was dug with a spade that had been used in England. The seeds from which these sprang were embedded in the dry earth adhering to the spade. Floating driftwood is quite an important means of dispersal, as can easily be understood; and the natives of some of the coral islands in the Pacific procure stones for their tools solely from the roots of drifted trees, the stones being a valuable royal tax. In this connection Darwin made the following interesting experiments. He found that when irregularly-shaped stones were embedded in the roots of trees, small parcels of earth were frequently enclosed in their interstices or 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 enclosed by the roots of an oak about fifty years old three dicotyledonous plants germinated. It is well known that in many cases a few days' immersion in sea-water is sufficient to kill seeds, but a number taken out of the crop of a pigeon which had floated on the water for thirty days nearly all germinated. Other aids to dispersal already referred to are wading birds, which frequent the muddy edges of ponds, and, if suddenly flushed, would be the most likely to have muddy feet. "Birds of this order wander more than those of any other, and they are occasionally found on the most remote and barren islands of the open ocean; they would not be likely to alight on the surface of the sea, so that any dirt on their feet would not be washed off; and when gaining the land they would be sure to fly to their natural fresh-water haunts. I do not believe," says Darwin, "that botanists are aware how charged the mud of ponds is with seeds; I have tried several little experiments, but will here only give the most striking case. I took in February three tablespoonfuls of mud from three different points, beneath water, on the edge of a little pond; this mud when dried weighed only six and three-quarter ounces. I kept it covered up in my studio for six months, pulling up and counting each plant as it grew. The plants were of many kinds, and were altogether five hundred and thirty-seven in number; and yet the viscid mud was all contained in a breakfast cup. Considering these facts, I think it would be an inexplicable circumstance if water birds did not transport plants to unstocked ponds and streams, situate at very distant points. The same agency may have come into play with the eggs of some of the smaller fresh-water animals."