The formation of the pigment granules in the cytoplasm still poses various problems. The cellular elements from which the pigment granules arise are not yet known with certainty; various theories have been developed in this respect, usually based on histological examination of pigmented tissues or tissue cultures. It is generally believed that the melanin in the pigmented cells is formed on a colorless protein-carrier. Some investigators (Meirowsky and Freeman, 1950-1951; Kadas, 1952) believe that the pigment granules originate from the nucleus; other authors (Luna, 1920; Rényi, 1924; Marakov, 1929; Sin-Ike, 1939; Woods, 1949) mention the mitochondria, and yet others (Ries, 1939; Fischer, 1937) state that the so-called lipochondria are the source. Hirsch (1953), investigating the origin of ocular pigment in rabbit and chick embryos, contended that the propigment granules, like the glandular secretions, arise from the Golgi system. Electron-microscopic investigations were made by Meirowsky and Freeman (1950-1951) and Weissenfels (1956).