LIFE OF JAMES DWIGHT DANA 

 The Growth of Coral Reefs 



The following paragraphs show the views of Professor 

 Dana in respect to the origin of coral sands and the reef 

 rock: 



" Very erroneous ideas prevail respecting the appear- 

 ance of a bed or area of growing corals. The submerged 

 reef is often thought of as an extended mass of coral, 

 alive uniformly over its upper surface, and as gradually 

 enlarging upward through this living growth ; and such 

 preconceived views, when ascertained to be erroneous by 

 observation, have sometimes led to scepticism with regard 

 to the zoophytic origin of the reef rock. Nothing is 

 wider from the truth : and this must have been inferred 

 from the descriptions already given. Another glance at 

 the coral plantation should be taken by the reader before 

 proceeding with the explanations which follow. 



" Coral plantation and coral field are more appropriate 

 appellations than coral garden, and convey a juster im- 

 pression of the surface of a growing reef. Like a spot of 

 wild land, covered in some parts, even over acres, with 

 varied shrubbery, in other parts bearing only occasional 

 tufts of vegetation in barren plains of sand, here a clump 

 of saplings, and there a carpet of variously colored flowers 

 in these barren fields such is the coral plantation. 

 Numerous kinds of zoophytes grow scattered over the 

 surface, like vegetation upon the land; there are large 

 areas that bear nothing, and others of great extent that 

 are thickly overgrown. There is, however, no green- 

 sward to the landscape ; sand and fragments fill up the 

 bare intervals between the flowering tufts : or, where 

 the zoophytes are crowded, there are deep holes among 

 the stony stems and folia. 



' These fields of growing coral spread over submarine 

 lands, such as the shores of islands and continents, where 

 the depth is not greater than their habits require, just as 

 vegetation extends itself through regions that are con- 

 genial. The germ, or ovule, which, when first produced, 

 is free, finds afterward a point of rock, or dead coral, or 

 some support, to plant itself upon, and thence springs 

 the tree or other forms of coral growth. 



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