EROSION of the gizzard lining of chicks fed simplified diets was described in 1931 by McFarlane, Graham and Hall. This pathological lesion was also found in chicks fed regular stock rations (Jungherr, 1935), and its relationship to the nutritional status was suggested at an early date (Almquist and Stokstad, 1936; Bird, et al., 1938).Bird and coworkers (1938) indicated that the growth of chicks was impaired by a deficiency of the “gizzard factor.” However, most investigators have observed no relationship between incidence of gizzard lesions and growth (Almquist and Stokstad, 1937; Esselen, 1939; Tepper and Bird, 1942a; Miller and Titus, 1942).The state of confusion regarding the anti-gizzard erosion factor was somewhat clarified by the report of Miller and Titus (1942). These authors studied the effect of many substances, either by inclusion in the diet of the parent stock or by injection into developing eggs. None of the vitamins, inorganic .