The structure of the egg‐shell of the cabbage root fly, Erioischia brassicae

Abstract

SUMMARYThe structure of the egg‐shell of Erioischia brassicae (Bouché) (Muscidae, Anthomyiinae) has been investigated with the aid of an electron‐microscope. The shell outside the hatching lines consists of three layers. The middle layer is a coarse meshwork, the struts of which are about 1–2μ thick. The upper layer consists of vertical columns that arise from the middle layer. These vertical columns or struts branch and anastomose at their apices in the plane of the shell and form a network that is the outermost wall of the shell. The struts of this outermost network are 0.01‐0.1μ thick and thus little of the outermost wall of the shell can be resolved with the light microscope. The inner layer consists of vertical columns usually 2–5μ long. These branch and anastomose at their apices in the plane of the shell and form a network that is the innermost wall of the shell. The median strip between the hatching lines lacks an outer network. The meshworks of the shell offer little protection against desiccation, and water, alcohols, and relatively mobile oils pass readily through the shell.