Note 4 — THE RIVAL CRUSOES;

The progress of vegetation is very curious in those islands, which are supposed by geologists to be thrown up from the bottom of the sea by volcanoes, or formed by the unceasing labours of the coral animalculi. These generally present at first a rocky surface, barren and arid. By degrees, a little soil is deposited by sea-fowl and birds of passage; on this at first grow the seeds of some of those minute plants, which are literally carried on the wings of the wind from countries that appear too far distant for any such conveyance. These plants flourish, fade, and are renewed by the seasons, until from their decayed parts is formed that fine vegetable mould which overspreads the more fertile surface of the earth. When this process is begun, if the land receives from the hand of some benevolent discoverer a few seeds of trees or plants to which the climate is congenial, the work of fertilization is rapidly accelerated; grass grows luxuriantly under the shade of the trees: verdure increases, and creeps farther and farther, till from one little spot, an oasis in the midst of a desert, the whole island becomes fruitful.