The relative levels of pair rule stripe expression vary between and along stripes. Plotted are averaged expression intensities of gene stripes for (a-c) ftz, (d) eve, (e) prd and (f) slp1. The various stripes of each gene show marked differences in expression profiles and each gene has a unique mode of variation in the direction of the d/v axis. The error bars give the 95% confidence intervals for the means. The data for eve expression were derived from n = 215 embryos at stage 5:50-100%, ftz from n = 155, prd from n = 17, and slp1 from n = 23.