Figure 2. A total of 263 eggs (N = 22 clutches) of water snake were checked for the positon of their embryos within 12 hours post-laying.

The proportions of eggs with top embryos (i.e. embryos located at the top of the egg) increased as non-linear function of clutch-size. Regression line is plotted as a quadratic fit (r = 0.75; F_{2, 19} = 12.27; P = 0.0004; equation y = −1.7925x + 0.2385x² + 29.3186).