  We apply the reconstruction technique of Nusser & Dekel (1992) to the
recently available Point Source Catalogue Redshift Survey (PSCz) in order to
subtract the phase correlations that are expected to develop in the mild
non-linear regime of gravitational evolution. We study the evolution of
isodensity contours defined using an adaptive smoothing algorithm in order to
minimize the problems derived from the non-comutivity of operators. We study
the genus curves of the fields thus obtained and concentrate on the evolution
of the amplitude drops, a meta-statistic able to quantify the level of
phase-correlation present in the field. In order to test the method and to
quantify the level of statistical uncertainty, we apply the method to a set of
mock PSCz catalogues derived from the N-body simulations of two 'standard' CDM
models, kindly granted to us by the Virgo consortium. We find the method to be
reliable in recovering the right amplitude drops. When applied to PSCz, the
level of phase correlations observed is very low on all scales ranging from
5h-1Mpc to 60 h-1Mpc, providing support to the theory that structure originated
from gaussian initial conditions.
