Organic components of the skeleton of scleractinian corals - evidence fromin situ acridine orange staining

Scleractinian skeleton is composed of mineral and organic phases. Using sta ining techniques (acridine orange dye) Johnston's (1980) pioneering observa tions of intraskeletal organic envelopes in Pocillopora damicornis coralla can be extended to two other coral reef genera i.e., Acropora and Favia. Th e concept of biologically mediated growth of coral skeleton stands in oppos ition to the purely mineralogic concept of fiber growth of Bryan and Hill ( 1941) widely applied until recently in geological and paleontological Liter ature. Presence of active mineralizing organic components within the skelet on explains various patterns of microstructural organization more accuratel y than the mineralogic concept of 'crystal growth competition' of Barnes (1 970) alone. Biochemical degradation of intraskeletal organic matrices is co nsidered to be involved in the initial diagenesis of coral skeleton, and ma y explain selective silicification of the late Cretaceous Coelosmilia sp. f rom Poland.