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they were found to have risen nearly to the surface, and to have attached themselves to the solid rock.

There is also a case mentioned of a ship in the Persian Gulf which, in the course of twenty months, had her copper encased with living coral to the thickness of two feet.

On the other hand, it is asserted, and we doubt not with equal truth, that many reefs do not seem to increase in size in the course of many years.

When a coral reef has reached the surface, the formation of an island instantly begins; but it necessarily takes a long time ere this island becomes habitable by man. Among the first plants that raise their heads to the sea-breeze is the