TROPICAL ISLANDS. 479 



passes it like a great moat Is thirty fathoms deep, and is shut out from the ocean by a 

 coral band at a distance of from half a mile to three miles. 



But there are coral reefs of far greater magnitude. The grandest is that extending 

 alonfy the north-east coast of Australia. Rising from an unfathomed ocean, it extends 

 for a thousand miles along the coast, with a breadth of from two hundred yards to a 

 mile, and at an average distance of twenty or thirty miles, though sometimes double 

 that space. This long, narrow lagoon is never less than ten fathoms deep, and often 

 six times as much, so that the '' Great Eastern," the hugest vessel that ever floated, if 

 it once passed through one of the openings in the reef, might sail as though in a tran- 

 quil harbor for a thousand miles in sight of land on either side, without its keel for an 

 instant reaching half way to the bottom. 



The direct influence of the ocean upon the islands of the Tropical World is great in 

 every respect. It gives an almost temperate climate to low lands lying under the 

 equator, and thus modifies their fauna and flora, in accordance with known laws of 

 nature. But the ocean and air in their currents also determine the vegetable, animal, 

 and human life of the islands of the Tropical World in an accidental manner. 



Time was when the volcanic islands of the tropics were masses of naked rock, the 

 coralline islands patches of barren sand. The elements disintegrated the surface of 

 the rock and ground the coral into soil. Some day a fruit, perhaps a cocoa or bread- 

 fruit, drifted along by currents, touched the island, or a bird swept far out to sea 

 having in its crop an undigested seed, rested its weary wing upon solid land. The 

 chance-planted fruit or seed took root, and grew, and produced its kind, and in time 

 the waste island was clothed with verdure. Other birds found a home in the new 

 forests, built their nests, and raised their young, so that the islands became populous 

 with the winged tribes. Animals, of course, could only rarely cross the waste of 

 waters Hence the comparative paucity of this form of life in islands remote from the 

 main land Swine were almost the only quadrupeds which the early European navi- 

 gators found in Polynesia ; and they were doubtless brought there by human means. 

 Mankind reached the islands in a like accidental manner. Perhaps a canoe from the 

 Malayan shores drifted upon the Fiji Islands, and its rowers became the progenitors of 

 the black cannibals ; or a junk from China or Japan was cast away upon Tahiti or 

 Hawaii. These wanderers, cut off" from intercourse with the rest of the world, 

 developed their barbarism or semi-civilization in their own way, under the influence 

 of altered conditions, climate and productions. The story of the " Bounty," and the 

 first settlement of Pitcairn's Island, too well known to require more than a passing 

 allusion, shows that such a canoe or junk voyage is altogether possible, and how widely 

 in the course of a single generation a group of isolated individuals deviate from their 

 original stock. 



