  In the framework of functional integration the non-leading terms to leading
eikonal behavior of the Planckian-energy scattering amplitude are calculated by
the straight-line path approximation. We show that the allowance for the
first-order correction terms leads to the appearance of retardation effect. The
singular character of the correction terms at short distances is also noted,
and they may be lead ultimately to the appearance of non-eikonal contributions
to the scattering amplitudes.
