. Corals and coral islands. Coral reefs and islands; Corals. LIFE AND DEATH IN CONCURRENT PROGRESS. 95 yps gradually disappear, and even their cells become superfi- cial and fade out. Trees of Madrepores may also have their limits—all below a certain distance from the summit being o dead ; and this distance will differ for different species. But this is not a limit to the existence of the zoothome, even. CAUIiASTK^CA FUKCATA. though a slender tree or shrub, or of its flourishing state; for the dead coral below is firm rock itself, often stronger than ordinary limestone or marble, and serves as
. Corals and coral islands. Coral reefs and islands; Corals. LIFE AND DEATH IN CONCURRENT PROGRESS. 95 yps gradually disappear, and even their cells become superfi- cial and fade out. Trees of Madrepores may also have their limits—all below a certain distance from the summit being o dead ; and this distance will differ for different species. But this is not a limit to the existence of the zoothome, even. CAUIiASTK^CA FUKCATA. though a slender tree or shrub, or of its flourishing state; for the dead coral below is firm rock itself, often stronger than ordinary limestone or marble, and serves as an ever-rising basement for the still expanding and rising zoophyte. But this death is not in progress alone at the base of the column or branch. Generally the whole interior of a corallum is dead, a result of the same process with that just explained. Thus, a Madrepora, although the branch may be an inch in diameter, is alive only to the depth of a line or two, the grow- ing polyps of the surface having progressively died at the low- er or inner extremity as they increased outward. The large domes of Astraeas, which have been stated to attain sometimes a diameter of ten or fifteen feet, and are. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Dana, James Dwight, 1813-1895. New York : Dodd & Mead
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Keywords: ., bookcentury1800, bookdecade1870, bookpublishernewyo, bookyear1872