70 ON CORAL REEFS AND ISLANDS. 



to gather into gardens the choicer varieties. Yet there are scenes 

 in the coral landscape, which justify the brightest coloring of 

 the poet: where coral shrubbery and living flowers are mingled 

 in profusion ; where Astreea domes appear like the gemmed tem- 

 ples of the coral world, and Madrepore vases, the decorations of 

 the groves ; and as the forests and flowers of land have their birds 

 and butterflies, so 



" Life in rare and beautiful forms 



Is sporting amid those bowers of stone," 



for fish of various hues, red, blue, purple, green, and other brilliant 

 shades, keep constant play, appearing and disappearing among 

 the branches. 



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 congenial. The germ or ovule, 

 which, when first produced, swims free, finds afterwards a point 

 of rock or dead coral to plant itself upon, and thence springs the 

 tree, or some other form of coral growth. 



The analogy to vegetation does not stop here. It is well 

 known that the debris of the forest, decaying leaves and stems, 

 and animal remains, add to the soil ; and that accumulations of 

 this kind are ceaselessly in progress : that by this means, in the 

 luxuriant swamp, deep beds of peaty earth are formed. So it is 

 in the coral mead. Accumulations of fragments and sand from 

 the coral zoophytes, and of shells and other relics of organic life, 

 are in constant progress ; and thus a bed of coral debris is formed 

 and compacted. There is this difference, that a large part of the 

 vegetable material consists of elements which escape as gases on 

 decomposition, whereas coral is itself an enduring rock-material 

 undergoing no change except the mechanical one of comminution. 

 The animal portion is but a mere fraction of the whole zoophyte. 



In these few hints, we have the whole theory of reef-making : 

 not a speculative opinion, but a legitimate deduction from a few 

 simple facts, and bearing close analogy to operations on land. 

 The coral debris and shells fill up the intervals between the coral 

 patches, and the cavities among the living tufts, and in this man- 

 ner produce the reef deposit, which is finally consolidated while 

 still beneath the water. 



The coral-zoophyte is especially adapted for such a mode of reef 

 accumulation. Were the nourishment drawn from below, as in 

 most plants, the solidifying coral rock would soon destroy all life : 

 instead of this, the tree is gradually dying below while growing 

 above ; and the accumulations cover only the dead portions. 

 Moreover, to prevent accident, where these accumulations do not 

 keep pace with the progress of death, organic incrustations cover 

 the lifeless trunk, and protect it from the dissolving waters. 



