  By using zero-norm states in the spectrum, we explicitly demonstrate the
existence of an infinite number of high energy symmetry structures of the
closed bosonic string theory. Each symmetry transformation (except those
generated by massless zero-norm states) relates infinite particles with
different masses, thus they are broken spontaneously at the Planck scale as
previously conjectured by Gross and Evans and Ovrut. As an application, the
results of Das and Sathiapalan which claim that sigma-midel is
nonperturbatively nonrenormalizable are reproduced from a stringy symmetry
argument point of view.
