  The strongly coupled limit of string scattering and the automorphic
construction of the graviton S-matrix is compared with the eleven dimensional
formulation of M-theory. In a particular scaling limit at strong string
coupling, M-theory is described by eleven-dimensional supergravity which does
not possess a dilaton, but rather a perturbative expansion in the gravitational
coupling and derivatives. The latter theory provides an off-shell description
of the string, upon dimensional reduction.
