528 On the Disjjersion and 



posit the seeds of shrubs and trees; every high tide, and, 

 still more, every gale, adds something to the bank ; the form 

 of an island is gradually assumed ; and last of all comes man, 

 to take possession. These various steps are distinctly marked 

 in an island situated on the north coast of New Holland, 

 Half-way Island is well advanced in the above progressive 

 state ; having been many years, probably some ages, above 

 the reach of the highest tides, or the wash of the surf in the 

 heaviest gales. " I [Captain Flinders] distinguished, how- 

 ever, in the rock which forms its basis, the sand, coral, and 

 shells formerly thrown up, in more or less perfect state of 

 cohesion. Small pieces of wood, pumice-stone, and other 

 extraneous bodies which chance had mixed with the cal- 

 careous substances when the cohesion began, were enclosed 

 in the rock, and in some cases were still separable from it 

 without much force. The upper part of the island is a mix- 

 ture of the same substances in a loose state, with a little vege- 

 table soil ; and is covered with the Casuarina, and a variety 

 of other trees and shrubs, which give food to the parroquets, 

 pigeons, and some other birds, to whose ancestors, it is pro- 

 bable, the island was originally indebted for this vegetation." 

 (Flinders's Survey of the Coast of New Holland.) From the 

 progress which this island has made, from natural causes, in 

 its vegetation, it is beyond a doubt that the winds and waves 

 are very efficient agents in spreading abroad the seeds of 

 plants (though, at the same time that we allow this, we must 

 not pass by unnoticed the length of time which the slow 

 advance of vegetation, when thus aided, requires), as has 

 certainly been the case with some species now spread over 

 the whole of Europe, but once entire strangers to its inhabit- 

 ants. Thus, the jErigeron canadensis (an instance which Lin- 

 naeus cites in confirmation of his theory,) was first introduced 

 into the gardens near Paris, from Canada; and then, the 

 seeds being carried by the winds, soon spread over all France, 

 Italy, Sicily, Belgium, and Germany : but this is a solitary 



the best of ray recollection, without twining stems, and much resembling 

 Phaseolus vulgaris in some one of its variations. This fact shows that birds 

 may become the agents of a very diffusive dispersion of plants ; for, 

 although it must be at once admitted, that, under natural circumstances, 

 these particular kidneybeans would have been consumed by the digestive 

 powers of the goose, it is not less true that seeds of an indigestible tex- 

 ture, and those encased in stony coverings, as in stone fruit, and very 

 minute seeds, which, in some cases, are numerously embedded in the 

 copious pulp of certain berries, can and do pass through the bodies of ani- 

 mals without any diminution of their powers of germination. Very nume- 

 rous facts may be collected to prove this position, were not its truth already 

 go familiar to many, as to render a collection of proofs unnecessary. — J. D. 



