FINE STRUCTURE AND COMPOSITION OF A SILICEOUS SPONGE SPICULE

Abstract

Siliceous spicules from Acarnus erithacus were studied using electron and light microscopy in conjunction with chemical analyses by gas chromatography. emission spectrography, and atomic absorption. Chemical data correlated with microscopy measurements indicate that there is sufficient carbon to provide a major fraction of the axial filaments as organic matter (assuming 40% carbon). The concentric ring structure reported earlier from light microscopy was studied on the electron microscopic level by utilizing carbon-platinum replicas of HF etched spicule cross sections. Ring spacings as small as 0.2-0.3 µ were detected using this technique. Correlation of chemical composition and fine structure is discussed with respect to the axial thread and the siliceous portions of the spicule.