Africa has never enlarged its domain through the aid of adjacent islands. Poor as it is in all coast indentations, it is just as poor in islands. Only a few insignificant ones, which have no close geological connection with the shore, are found here. The sporadic groups found in the Atlantic and Indian Oceans are almost exclusively the product of subterranean forces, and are entirely unlike the stratified lime and sandstone formations of the coast. There is, therefore, no close connection between the inanimate nature of continent and islands and their respective populations; no physical conditions have imposed upon them a common historical development. Only the Canary Islands, southwest of the Atlas Mountain range, and Madagascar, could be regarded as at all exceptional to this. But the nine Canaries are relatively extremely small, embracing but about 3000 square miles in all; much too small to exercise any important influence, or to harbor a large population. Besides, they are separated from the main land by marine currents, which would prevent any very important reaction, however large the islands in themselves might be. The Cape Verd islands, embracing only about 1750 square miles, stand in yet more unfavorable relations to the main land. So, too, the solitary islands of St. Helena and Ascension, and in the Indian Ocean the scattered groups of the Camara, Amirante, and Seychelle islands, embracing all together but 3300 square miles, and Socotra, about 1750 square miles. Only Madagascar would be large enough to enrich the continent essentially, if it were nearer to the main land. But it is separated from it by the broad and dangerous Mozambique Channel; both, therefore, have remained without mutual relations; their populations are entirely unlike, and there has been no exchange of productions between them. Madagascar is, therefore, only apparently, and by the apparent contiguity of the mass, a neighbor of Africa; but, in reality, _i.e._ as it relates to the organic unity of all the various parts of the globe, it is far more intimately connected by the system of marine currents to the Malayan Archipelago, southeast of Asia, than to Africa. Entirely different is it with the island system of Asia. The eastern and southern sides are remarkably characterized by the profuse numbers of islands found there. It might be said, that what Africa lacks in this regard, Asia more than supplies. On the Asiatic coast they appear in such vast numbers that they have been called, in contrast with the Old and New Worlds, the Island World, or Polynesia. They appear under the most varied conditions—in long rows, in massive groups, and here and there singly. They begin with the North Polar islands, and pass southward in unbroken succession past the equator as far as the tropic of Capricorn. The Aliaska chain connects the northwest coast of America with Kamtchatka; it comprises over 100 islands, and embraces about 7660 square miles.