Fig. 3. Cryoinjury to R. sylvatica erythrocytes frozen at -4 or -6°C in PBS (no additive) or PBS containing 40 mmol l^-1 urea, 40 mmol l^-1 glucose or 40 mmol l^-1 glycerol. Damage was assessed as the percentage of cells lysing. Within temperature-treatment groups, mean values (± S.E.M., N=7 replicates per group) identified by different letters differed significantly (repeated-measures ANOVA/Bonferroni; P<0.05).