A study of the fundamental cause of natural translucent areas in egg shells

Abstract

Synopsis On candling, eggs often show translucent areas sometimes known as mottling. This is caused by local accummulations of moisture in the shell. A study of natural or “normal” translucence, as distinct from “accidental” translucence, has been made. It was observed that freshly laid eggs have wholly translucent shells which, on drying, develop opacity, often leaving some areas translucent. An early association between natural translucence and an increased shell matrix protein content has been confirmed, and a study of the distribution of this matrix in radial sections of shell has revealed a difference between opaque and translucent shell. Further there was a difference in the porosity of opaque and translucent shells. These findings could be explained by the presence in opaque shells of a layer of shell low in organic matter, which appears to hinder the passage of moisture through the shell.