The Luminous Organs and the Light of the Pholades

Abstract

ABSTRACT In continuation of the studies already made on luminous animals, I now present to the academy a work on pholades, concerning particularly the most ordinary species of our seas, namely, the Pholas dactylus L. The phosphorescent properties of these molluscs has been for some time known, and the luminous clouds which they spread in water when touched or moved. Pliny describes this phenomena in a special paragraph of his ninth book.1 His observations were afterwards confirmed by many authors, and Reaumur also wrote on this matter,2 expressing the belief that the outer surface of the pholad creates this luminous matter, illuminating the object it touches, and the water in which one washes one’s hands. According to Reaumur this same matter if dried shines again when wet. Monti, Beccari, and Galeati, as also their contemporary, Reaumur, were much occupied on the subject, and made observations which scarcely differ one from another. They maintain that pholades shine most when in milk. The authors whom I cite in my memoir confine themselves to describing the phenomenon without indicating its precise situation.