GEOGRAPHICAL DISTRIBUTION OF ANIMALS
mals, and the fact that the absence of such animals is due to their inability to reach the islands, except by human aid, is shown by the oft-repeated results of artificial introduction. Rats, mice, rabbits, swine, goats, cattle, and horses, when allowed to run wild on such islands, have thrived and multiplied exceedingly, showing that no unfavourable factor in the environment prevented their presence.
The fact that the oceanic islands really have been supplied with their plants and animals by the more or less accidental agency of the sea and the winds is indicated by a remarkable instance, of which we have the whole history, for it took place within recent years. In the Straits of Sunda, between Java and Sumatra, there is a volcanic island called Krakatau, which, in the summer of 1883 was the scene of a series of the most tremendous volcanic explosions that have occurred within historic time. In consequence of this terrific outburst, most of the island was destroyed and such parts of it as remained above water were so deeply buried by volcanic ash that all animal and vegetable life was completely destroyed; apparently not a living thing was left. Yet in twenty years, or less, the desolate island was restocked by the winds and ocean currents. The late Professor Selenka, of Munich, visited Krakatau some years after the catastrophe, and wrote of it:
Under the shade of a Casuarina, among cocoanut palms and thickets as high as a man's head, I found, to my astonishment, an active animal life of spiders, flies, bugs, beetles, and butterflies; even lizards half a yard in length animated the peaceful picture. All these plants and animals were brought hither by wind and water from Java and Sumatra, replacing the vanished world in the course of a few years.
If the living things on oceanic islands, animal and vegetable, were not created especially for them, they must have
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