Variation in some shell membrane characteristics over different parts of the same shell

Abstract

Synopsis The variation in shell membrane thickness (μ), membrane weight (mg./cm.2), membrane nitrogen (μg. N/cm.2) and packing index (μg./cm.2/μ) from the broad pole, excluding the air space, to the narrow pole of the same egg has been studied. The pattern of variation for a given characteristic was the same in different eggs from the same bird. Two thickness patterns were found. In Group I thickness decreased from the B collar to the equator, increased again to the G collar and then decreased sharply at the H cap. In Group II the increase from the equator to the G collar was replaced by a continued, but less‐marked, decrease. There was a high, positive correlation between weight and nitrogen, but the relationship between weight and thickness varied within and between eggs. All eggs showed a very similar pattern of packing index variation, decreasing from the B to about the C collar and then increasing to the H cap, the pattern being the same whether measurements were made on wet or dry membranes.