Dividing egg of the jellyfish (Spirocodon saltatrix showing birefringent spindles. The arrow indicates the direction of the compensator slow axis. AS the cell is rotated 90 degrees with respect to the axis, the contrast of the spindles change from dark to light.
See: S. Inoue and K. Dan (1951) Birefringence of the dividing cell. J Morph 89:423-455.