THE STRUCTURE OF EPIDERMAL MELANOPHORES IN FROG TADPOLES

Color changes in animals have been the object of much investiga tion. Parker (1930), in an historical account of the subject, indicates that color changes have been recognized from very early times and are still a fertile field for study. Many problems concerning the reac tions of pigment cells have been worked out. The structure of the pigmentary elements, however, has been difficult to determine. The main currents of opinion concerning the structure and the mechanism of “¿expansion―and “¿contraction―of the melanophores may be ascer tained from recent papers by Hewer (1923), Matthews (1931), and Perkins and Snook (1932). Hewer states that no fewer than one hundred and fifty papers have been published on color changes of amphibians alone. Even with this extensive work on amphibians little mention is made of the epidermal melanophores of frogs and their tadpoles. In the frogs and tadpoles that I have studied, Rana clamitans,