Changes in structure of the limiting membrane and in oxygen permeability of the chicken egg integument during incubation

1. Oxygen permeabilities (K_O2 ) of the shell and shell membranes of fertile and infertile chicken eggs were measured at 37.5 °C and a relative humidity of 0.60 throughout 14 d incubation, with turning. The K_O2 of the shell and membranes of infertile eggs was around 1.0 × 10^?7 cm³ O₂STP sec^?1 cm^?2 Torr^?1 (1 Torr = 133.322 Pa) throughout incubation. With fertile eggs, from which there was a linear loss of water during incubation, the K_O2 of the shell and shell membranes was about 1.0 × 10^?7 cm³ O₂STP sec^?1 cm^?2 Torr^?1 for the first four days of incubation. Thereafter the majority of shells and membranes had a K_o2 of about 1.0 × 10^?6 cm³ O₂STP sec^?1 cm^?2 Torr^?1.

2. A diminution of the Na⁺ and K⁺ content of the shell membranes of fertile eggs was not associated with changes in the dimensions of the glyco‐protein mantle on the cores of the individual fibres of the membranes. There was, however, a progressive deterioration in the limiting membrane of fertile but not of infertile eggs.

3. It was concluded that changes in the O₂ resistance of the integument of fertile eggs were not a product of change in either of the shell membranes but of damage caused to the limiting membrane by the chorioallantois.