Fig. 3. Activities of ß-1,4-glucosidase activities in digestive juice of G. natalis and D. hirtipes in the presence (stars) and absence (circles) of 20 mmol l^-1 glucono-D-lactone. For both G. natalis and D. hirtipes, the ß-1,4-glucosidase activity increased with increasing cellobiose concentrations and was higher in the absence of glucono-D-lactone (P<0.05; two-way ANOVA). For ß-1,4-glucosidase activity from D. hirtipes, there was a significant interaction (P<0.05) between cellobiose concentration and treatment (two-way ANOVA). Uninhibited ß-1,4-glucosidase activities from D. hirtipes were higher than uninhibited ß-glucosidase activities from G. natalis (P<0.05; two-way ANOVA).