Published online by Cambridge University Press: 27 March 2009
1. Egg-shells from six inbred lines of Brown Leghorn fowls were examined for porosity and thickness in March and in July.
2. For both characters studied the variation between-line means was found to be significant.
3. The line means for thickness were with a single exception lower in July.
4. Porosity coefficients increased from March to July.
5. No significant relationship between shell thickness and porosity was found in either season. Line differences in porosity values are therefore attributable to variations in other properties of the shell.