$A(\Gamma)$ corresponds as one non-unique possibility to a system in which $\langle (\Delta x(t) )^{2} \rangle$ increases linearly in time.

It has repeatedly been found that $g^{(1s)}(q,t)$ decays in time as the stretched exponential of eq \[eq:gisqeext\]. If one interpreted this time dependence by applying eq \[eq:g1swrong\], one would conclude $$\langle (\Delta x(t) )^{2} \rangle = \theta t^{\beta}.
         \label{eq:subdiffusive}$$ In the common case $\beta < 1$, from eq \[eq:subdiffusive\] one would infer that the mean-square particle displacement increases less rapidly at large times than would be the case for simple diffusion, a behavior that has been termed ’subdiffusive’ motion. The inference is incorrect. A more reasonable interpretation for $\beta <1$ is that diffusion in the complex fluid is created by modes having a range of relaxation times, some longer than others, the contribution of the slower modes to the spectrum becoming more important at longer times.

It is not suggested that there cannot exist subdiffusive motion. Such motion has unambiguously been observed experimentally. Amblard, et al.,[@amblard1996a] studied probe motion in f-actin solutions, using magnetic tweezers and video microscopy. Small-bead motion was diffusive; larger-bead diffusion was subdiffusive with $\beta \approx 3/4$. The non-classical drag forces for diffusive motion and for driven 