Figure 1. Mass evolution was measured in 28 eggs and hatchlings of the grass snake N. natrix (open circles) and 51 eggs and hatchlings Viperine snake N. maura (grey triangles).

A repeated measure ANOVA with species as factor and egg/hatchling mass as the repeated measure over time yielded F_{7, 469} = 7.38; P < 0.001. Egg masses were measured every week. Snake masses were measured at birth and 3 weeks old. Snakes were unfed. Means ± SE are plotted.