502 GENERAL EFFECTS OF CORAL-GROWTHS. 



coral, either on the sides of this mountain, or on the summit of 

 the volcanic crater, it is a reasonable inference that the island 

 must have been upraised, to the whole amount of the elevation 

 of the ancient ridge of coral above the reefs at present in course 

 of formation, at one movement. In the bands of the Pacific 

 Ocean, regarded by Mr. Darwin as areas of elevation, no lagoon 

 islands or barrier reefs are met with ; but the shores are fringed 

 by skirting reefs ; and active volcanic changes are not of infre- 

 quent occurrence. 



1147. The following remarks by Mr. Darwin form a very 

 appropriate conclusion to this part of our subject : " It is not 

 that the ocean spares the rotk of coral ; the great fragments 

 scattered over the reef, and accumulated on the beach, whence 

 the tall cocoa-nut springs, plainly bespeak the unrelenting power 

 of its waves. Nor are there any periods of repose granted. The 

 long swell, caused by the gentle but steady action of the trade- 

 wind always blowing in one direction over a wide area, causes 

 breakers, which even exceed in violence those of our temperate 

 regions, and which never cease to rage. It is impossible to 

 behold these waves, without feeling a conviction that an island, 

 though built of the hardest rock, let it be porphyry, granite, or 

 quartz, would ultimately yield and be demolished by such irre- 

 sistible forces. Yet these low insignificant coral islets stand and 

 are victorious ; for here another power, as antagonist to the 

 former, takes part in the contest. The organic forces separate 

 the atoms of carbonate of lime one by one from the foaming 

 breakers, and rear them up into a symmetrical structure. Let 

 the hurricane tear up its thousand huge fragments ; yet what 

 will thus tell against the accumulated labour of myriads of archi- 

 tects at work day and night, month after month. Thus do we 

 see the soft and gelatinous body of a polypus, through the agency 

 of the vital laws, conquering the great mechanical power of the 

 waves of an ocean, which neither the art of man nor the inani- 

 mate works of nature could successfully resist."* 



1148. Much discussion has taken place in regard to the 

 sources, from which the Coral-polypes obtain the enormous quan- 



* Darwin's Journal, p. 548. 



