  The phenomenon of clustering of galaxies on the basis of correlation
functions in an expanding Universe is studied by using equation of state,
taking gravitational interaction between galaxies of extended nature into
consideration. The partial differential equation for the extended mass
structures of a two-point correlation function developed earlier by Iqbal,
Ahmad and Khan is studied on the basis of assigned boundary conditions. The
solution for the correlation function for extended structures satisfies the
basic boundary conditions, which seem to be sufficient for understanding the
phenomena, and provides a new insight into the gravitational clustering problem
for extended mass structures.
