Frequency of supernumerary limbs following blastemal rotations in the newt

An examination has been made of the supernumerary limbs produced as a result of tissue interaction following ipsilateral rotation of blastemas at the stage of early digits. The frequency of supernumerary limb formation peaks sharply at angles of rotation near 180°, where tissues from widely separated circumferential locations are opposed. This behavior is compatible with predictions of the polar coordinate model with positional values clustered in the anteriorventral quadrant of the circumference (French et al., '76; Bryant and Iten, '76).