Tennis Ball Effect in fertilizable eggs. (A) Jelly-coated egg not exposed to the magnet. Note the position of the white equatorial line. The overall appearance and the pigmentation pattern are indistinguishable from the jelly-coated eggs exposed to the magnet and from the dejellied controls not exposed to the magnet (not shown). (B-D and F) Cysteine-dejellied eggs after exposure to the magnet, with altered cortical pigmentation. (B) Vegetal view of a late TBE I, with the equatorial line descended towards the vegetal pole. (C) Lateral view of an intermediate TBE II, showing the tongue that reaches out from the descended equatorial line. (D) Animal view of late TBE II, with the tongue from the equatorial line having reached the animal pole. (E) Tennis ball. (F) Orientation of the TBE in the magnetic field. The magnetic field's central axis (z) was perpendicular to the image plane. The images in (A), (C-D) and (F) were taken prior to and the one in (B) after fixation.