Published online by Cambridge University Press: 26 July 2017
Until the mid-1960's, procedures for studying shell microstruetures were laborious and, for many purposes, unsatisfactory. Depositional surfaces were observed with binocular microscopy, and shell material was embedded in various media, sectioned, mounted on a glass slide, and observed with ordinary light and polarized light microscopy. These procedures revealed the major microstructural organization of shell layers and their optical crystallographic properties, but they provided little information regarding what is now termed shell ultrastructure. Nevertheless, these techniques provided the basis for a number of important pioneering works on molluscan shell microstructure between 1921 and 1967.