  We have generalized the four-dimensional Langevin approach used in our
previous works for the description of fission process to the five-dimensional
by considering the neck parameter $\eps$ in the two-center shell model shape
parametrization as an independent dynamical variable. The calculated results
for the mass distribution of fission fragments are in better agreement with the
available experimental data. In particular, the transition from the
mass-symmetric to mass-asymmetric fission via the triple-humped distribution in
fission of Thorium isotopes is well reproduced.
