Development of preferred orientation in the eggshell of the domestic fowl

Preferred orientation in the shell of the domestic fowl is shown by x-ray diffractometry to develop gradually throughout the shell, beginning immediately after the start of shell deposition and reaching a maximum at the exterior surface. Only 2 out of 20 shells examined exhibited a single preferred orientation: This was one in which the pole of the (001) plane lies parallel to the shell surface normal. The remaining shells had two preferred orientations present simultaneously, one in which the (001) pole is parallel and the other in which the (104) pole is parallel to the surface normal. Previous work has resulted in conclusions that are in conflict with these; they are discussed in relation to the present work.