Fig. 4. The fractional absorptions of three carbohydrate probes in Egyptian fruit bats, Rousettus aegyptiacus (circles, N=11) and Sprague-Dawley laboratory rats [squares, N=6; rat data from Lavin et al. (Lavin et al., 2004)]. 3-OMD-glucose (194 Da; closed symbols) is absorbed both actively and passively; L-rhamnose (164 Da) and cellobiose (342 Da) are absorbed passively (open symbols). For rats, lactulose (342 Da), an isomer of cellobiose, was used as a probe instead, and was assumed to behave similarly to cellobiose. Asterisks indicate statistically significant differences (P<0.05) between rats and R. aegyptiacus (see main text); error bars are ±1 s.e.m. (some error bars are smaller than the symbols). Both species show high absorption of 3-OMD-glucose, and both show decreasing absorption of the passively absorbed probes as probe size increases; however, passive absorption by R. aegyptiacus was significantly higher than that by rats for both passively absorbed probes.