1. Responses of melanophores to injections of adrenalin or L-noradrenalin have been examined with and without prior injection of ergotamine.
2. Responses of the melanophores of isolated skin preparations in solutions containing adrenalin or L-noradrenalin have been examined with and without prior injections of, or direct exposure to, solutions of ergotamine.
3. No reversal of response could be found in any of the above cases.
4. Responses of melanophores following injections of Rogetine (an alternative adrenergic blocking agent) are quite unlike those after ergot but closely resemble those after atropine.
5. It is concluded that it is unjustified to assume that drugs produce similar effects in fishes and in mammals. The case for double innervation of melanophores is therefore still unproven.