Rate of addition of leg-bearing segments through embryonic development. (A) Plots show the segment number each day for single embryos (each represented by a different colour) (n = 22); interrupted or fragmentary lines correspond to embryos for which sure daily data were not available. (B) Plots show the daily averaged segment number for the embryos of (A) having a leg-bearing segment (LBS) number value of 41 to 43 at Stage 6.1 (blue line, ‘mean st 6.1 43 LBS’) (n =14) and for the embryos of (A) having a LBS number value of 44 to 45 (red line, ‘mean st 6.1 45 LBS’) (n =8). (C) Plot comparing the red line of (B) (‘mean st 6.1 45 LBS’) with a selection (n =9) of those embryos whose sex has been determined at stage adolescens I. The plot shows that the trend of the daily mean values of (B) is a precise representation of the trend of known female individuals, with an adult LBS number of 49. LBS values at Stage 6.1 are marked by an arrow in (A) and are in yellow in (B) and (C) (specific values indicated in (B)). Negative LBS values indicate anterior, nonleg-bearing segments: 2, first maxilla segment; –1, second maxilla segment; 0, maxilliped segment.