Fig. 4. Relationships between the duration of the exposure to –5°C and the concentrations of sodium (A,B) or potassium ions (C,D) in either haemolymph (A,C) or fat body cells (B,D) in the adults of Pyrrhocoris apterus belonging to three different acclimation groups (LD, SD, SDA; see Fig. 1). Each data point represents a mean ± S.E.M. of 6 samples (LD) or 3 samples (SD, SDA), each consisting of pooled tissues taken from 10 insects. The probabilities that slopes of linear regressions deviate from zero were: (A) LD, P=0.016; SD, P=0.724; SDA, P=0.274; (B) LD, P=0.527; SD, P=0.602; SDA, P=0.917; (C) LD, P<0.001; SD, P=0.003; SDA, P<0.002; (D) LD, P=0.142; SD, P=0.009; SDA, P=0.017.