EXCITEMENT DARKENING AND THE EFFECT OF ADRENALINE ON THE MELANOPHORES OF XENOPUS LAEVIS

Abstract

Among the Amphibia Xenopus laevis is an exception with regard to its melanophore reactions following excitement stimuli and epinephrine injns. Contrary to other Amphibia, light-adapted Xenopus react to excitement stimuli with darkening. Epinephrine has a diphasic effect on the melano-phores of Xenopus; following epinephrine injns. the melano-phores of dark-adapted animals contract, whereas those of light-adapted animals expand. In expts. with extirpated legs a direct action of epinephrine on the melanophores of Xenopus can be demonstrated.