The function of the cuticle in relation to the porosity of eggs

The porosity of egg is measured by the usual practice of estimating the weight loss under standard conditions. The porosity coefficient is expressed as the loss in weight in mg. per sq. cm. of egg surface per 24 hr. at 37°C. P coeff.=mg. cm. 2 24 hr. 37°. 2. It is shown that eggs of even curvature approximate closely to the ideal mathematical form of two hemi-prolate spheroids, differing in their eccentricities and meeting in the plane of their common minor axes. On this assumption the divergence between the observed and calculated long perimeter is only +0·618 per cent (five eggs) and between the observed and calculated volumes+3·78 per cent (seventy eggs). 3. It is explained how, by taking the specific gravity of the egg to correct for departures from the theoretical form, it is possible to calculate the surface area with an error not exceeding 1 per cent.