Recent observations by Cooper et al. of the charge distributions in 166Er and 176Yb bring to mind an old idea that the ground state of finite nuclear matter may exhibit spatially periodic mass-density and charge-density modulation. A feasible experiment employing a polarized 165Ho target is proposed. A spatially periodic charge modulation could most easily be detected by Bragg scattering of high-energy electrons. NUCLEAR STRUCTURE Charge distribution; collective instabilities; electron scattering.