  Recent data on the structure function F_2(x,Q^2) at small values of x are
analysed and compared with theoretical expectations. It is shown that the
observed rise at small x is consistent with a logarithmic increase, growing
logarithmically also with Q^2. A stronger increase, which may be incompatible
with unitarity when extrapolated to asymptotically small values of x, cannot be
inferred from present data.
