It is the purpose of this paper to prove the following theorem: Let \(M\) be a compact hypersurface of a complete, simply connected space \(N\) of constant curvature, and suppose that all geodesics of \(M\) are congruent in \(N\). Then \(M\) is an extrinsic sphere of positive curvature. The article contains many nice geometric ideas. Unfortunately it is not written carefully. It seems, however, that the defects can be correceted.