  We further clarify how scalar metric perturbations are amplified in an
inflationary cosmology. We first construct a simple, analytic model of an
inflationary cosmology in which the expansion scale factor evolves continuously
from an inflationary era to a radiation-dominated era. From this model, it is
clear to see how scalar perturbations are amplified. Second, we examine the
recent claims of Grishchuk, and the reply by Deruelle and Mukhanov, regarding
the evolution of scalar perturbations through an abrupt transition in the
equation of state of the cosmological fluid. We demonstrate that the ``standard
results'' regarding the amplification of scalar, density perturbations from
inflation are valid.
