Pigments and Chromatophore Reactions of Polycelis nigra and Planaria lugubris

Abstract

IN 1938, I observed that the chromatophores of Planaria lugubris and Polycelis nigra expand in light and contract in darkness. My experiments have recently been repeated with similar results; and in addition the effects of adrenaline and ergotine have been noted. In every case the chromatophores showed normal primary responses (as do the chromatophores of less primitive animals, for example, leeches¹ and sea urchins²). They had no influence upon the general coloration of the animals.