  In the present paper which a sequel to dg-ga/9511005 and dg-ga//9610013 a
global Weierstrass representation of an arbitrary closed oriented surface of
genus $\geq 1$ in the the three-space is constructed. The Weierstrass spectrum
of a torus immersed into $R^3$ is introduced and finite-zone planes as well as
finite-zone solutions to the modified Novikov-Veselov equations are
constructed.
