Figure 3.

Iridescence of eggshells. Specular reflectance of a T. major eggshell fragment at different angles of incidence before (a) and after (b) treatment with EDTA to remove the cuticle. Shown are specular reflectance curves at 5° angle increments between 10° (dark blue) and 50° (light blue) from coincident normal (θ = 0°). (c) Hue, the wavelength (nm) with maximum reflectance, of the primary blue–green peak as a function of the angle of specular incidence (θ = 0° at coincident normal). Shown are means ± s.e.m. at different angles for three T. major eggs (blue symbols), one T. major egg following treatment with EDTA (black circles) and a G. gallus egg (open squares). (Online version in colour.)