On the arrangement of aragonite crystals in the inner layer of the nacre

Abstract

It was reported in the preceding paper1) that the nacreous layer of the pearl oyster, Pinctada martensii, was composed of the mosaic structure of minute aragonite crystals which arranged their orthorhombic b axes parallel or nearly parallel to the horizontal growth direction of the shell. But the crystal arrangement differed from portion to portion of the nacre, and among individual shells. In this case, special attention has been paid to the relation between the shell development and the arrangement of the crystalographic axis, and to the spiral growth of aragonite crystals on the nacreous surface. In this paper, the relationship among the horizontal growth of the shell, the arrangement and the growth pattern of small aragonite crystals on the inner shell surface was investigated for the several pearl oysters of the genus Pinctada with X-ray diffraction and polarizing microscope. © 1959, The Japanese Society of Fisheries Science. All rights reserved.