  We study Lauricella's hypergeometric function F_C by using twisted
(co)homology groups. We construct twisted cycles with respect to an Euler-type
integral representation of F_C. These cycles correspond to 2^m linearly
independent solutions to the system of differential equations annihilating F_C.
Using intersection forms of twisted (co)homology groups, we obtain twisted
period relations which give quadratic relations for Lauricella's F_C.
