  We derive the vertex operators that are expected to govern the emission of
the massless d=11 supermultiplet from the supermembrane in the light cone
gauge. Our results immediately imply the linear coupling of matrix theory to an
arbitrary supergravity background to all orders in anticommuting coordinates.
Finally we address the definition of n-point tree level and one-loop scattering
amplitudes. The resulting 3-point tree level amplitudes turn out to agree with
d=11 supergravity and are completely fixed by supersymmetry and the existence
of a normalizable ground state.
