1888.] Mr. John Murray on Coral Beefs, dc. 251 



WEEKLY EVENING MEETING, 



Friday, March 16, 1888. 



William Huggins, Esq. D.C.L. LL.D. F.R.S. Vice-President, 

 in the Chair. 



John Murray, Esq. 



Structure, Origin, and Distribution of Coral Beefs and Islands. 



The picturesque beauty of the coral atoll, seated 'mid a waste of 

 troubled waters, with its circlet of living green, its quiet, jDlacid 

 lagoon, and its marvellous submarine zoological gardens, has long 

 been celebrated in the descriptions of voyagers to troj)ical seas. The 

 attempt to arrive at a correct explanation of the general and charac- 

 teristic form and features of these reefs and islands has, for an 

 equally long period of time, exercised the ingenuity of thoughtful 

 men. 



Coral reefs are the most gigantic and remarkable organic accu- 

 mulations on the face of the earth. They are met with in certain 

 tropical regions, and are huge masses ,of carbonate of lime, secreted 

 from ocean waters by myriads of marine organisms. While the 

 great bulk of the reef consists of dead corals, skeletons and shells, the 

 outer surface is clothed with a living mantle of plants and animals. 

 This is especially the case on the outer and seaward face of the reef, 

 where there are, at all times, myriads upon myriads of outstretched 

 and hungry mouths, and not the least interesting questions connected 

 with a coral reef are those relating to how these hungry mouths are 

 satisfied. 



It is to the power of these organisms of secreting carbonate of 

 lime from sea water — building up and out generation after generation 

 on their dead selves — that the coral reef owes its origin. So wonder- 

 ful and unique is the result, tbat combination for a definite end has 

 sometimes been attributed to these reef-builders. 



There is, however, another process ever at work in the ocean, in 

 a sense antagonistic to that of secretion of carbonate of lime by 

 organisms, which has much to do in fashioning the more characteris- 

 tic features of coral reefs. This is the solution of all dead carbonate 

 of lime shells, skeletons, and calcareous debris, wherever these are 

 exposed to the action of sea water. As soon as life loses its hold on 

 the coral structures, and wherever these dead carbonate of lime 

 remains are unprotected by rapid accumulation, they are silently, 

 surely, and steadily removed in solution. This appears to be one of 

 the best established oceanographical facts, and any theories concern- 

 ing the general economy of the ocean which fail to take account of 



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