Fig. 5. Metabolic rates (in W) of mammalian cells in vivo (blue line) and cultured in vitro (red line) plotted as a function of organism mass (M_b in g) on a log-log scale. While still in the body and constrained by vascular supply networks cellular metabolic rates scale as M_b^-1/4. When cells are removed from the body and cultured in vitro, their metabolic rates converge to a constant value predicted by theory (West et al., 2002b). The two lines meet at the mass of the smallest mammal (the shrew with mass 1 g, as predicted). Figure taken from West et al. (2002b) with permission.