  The symmetry energy, temperature, density and isoscaling parameter, in
$^{58}$Ni + $^{58}$Ni, $^{58}$Fe + $^{58}$Ni and $^{58}$Fe + $^{58}$Fe
reactions at beam energies of 30, 40 and 47 MeV/nucleon, are studied as a
function of excitation energy of the multifragmenting source. It is shown that
the decrease in the isoscaling parameter is related to the near flattening of
the temperature in the caloric curve, and the decrease in the density and the
symmetry energy with increasing excitation energy. The decrease in the symmetry
energy is mainly a consequence of decreasing density with increasing excitation
rather than the increasing temperature. The symmetry energy as a function of
density obtained from the correlation is in close agreement with the form,
E$_{sym}(\rho)$ $=$ 31.6 ($\rho/\rho_{\circ})^{0.69}$.
