Fig. 5. Representative efflux curves for ²²Na at different developmental stages of Hemigrapsus crenulatus. Eggs were pooled from five ovigerous crabs, batch-labelled in ²²Na-labelled seawater for 24 h, and washed in groups of 4–8 in unlabelled 100% seawater for varying times. (A) Egg radioactivity (expressed as nmol exchangeable sodium at the radioactive concentration of the loading medium) is shown on a linear scale; (B) natural logarithm of the radioactivity is plotted. Each point is the mean (± s.e.m. in the linear plot) of 5–8 groups of eggs sampled at each time. Trend lines were fitted by single or bi-exponential regression (see Materials and methods).