  We prove the doubling property of L-caloric measure corresponding to the
second order parabolic equation in the whole space and in Lipschitz domains.
For parabolic equations in the divergence form, a weaker form of the doubling
property follows easily from a recent result, the backward Harnack inequality,
and known estimates of Green's function. Our method works for both the
divergence and nondivergence cases. Moreover, the backward Harnack inequality
and estimates of Green's function are not needed in the course of proof.
