  Results on the derivative of log(F_2) with respect to log(x) at fixed Q^2 are
presented. The measured derivatives are within errors independent of x for Q^2
>= 0.85 GeV^2 and increase linearly with log(Q^2) for 0.0001 <= x <= 0.01 and
Q^2 >= 3 GeV^2.
  The results are based on preliminary and published H1 data which at Q^2 below
2 GeV^2 are combined with NMC and ZEUS data.
