OSAWA, I. 1912. Cytological and experimental studies in citrus. Tokyo Imp. Univ. Col. Agric. Jour. 4:83-116. PICKETT, W. F., AND C. J. BIRKELAND. 1942. The influence of some spray materials on the internal structure and chlorophyll content of apple leaves. Kansas Agric. Exp. Sta. Tech. Bull. 53:1-54. ROLFE, W. A. 1930. Sulphuring citrus trees. Victoria Dept. Agric. Jour. 28:732-733. SCOTT, F. M., M. R. SCHROEDER, AND F. M. TURRELL. 1948. Development, cell shape, suberization of internal surface and abscission in the leaf of the Valencia orange, Citrus sinensis. Bot. Gaz. 109:381-411. SINCLAIR, W. B., AND D. M. ENY. 1947. Ether-soluble organic acids and buffer properties of citrus peels. Bot. Gaz. 108:398-407. THIMANN, K. V., AND W. D. BONNER. 1949. Experiments on the growth and inhibition of isolated plant parts. II. The action of several enzyme inhibitors on the growth of the Avena coleoptile and on Pisum internodes. Amer. Jour. Bot. 36:214-222. THOMAS, M. D., R. H. HENDRICKS, T. R. COLLIER, AND G. R. HILL. 1943. The utilization of sulphate and sulphur dioxide for the sulphur nutrition of alfalfa. Plant Physiol. 18:345-371. TURRELL, F. M. 1950. A study of the physiological effects of elemental sulphur dust on citrus fruits. Plant Physiol. 25:13-62. AND M. B. CHERVENAK. 1950a. Metabolic products of elemental sulfur 35 applied to lemons as an insecticide. Advances in Chem. 1:250-259. , AND . 1950b. Effect of zinc-sulphur spray on the chlorophyll, phaeophytin, and sulfur content of orange leaves. In press. TYDEMAN, H. M. 1941. The inheritance of susceptibility to sulphur damage in families of seedling apples. Jour. Pomol. and Hort. Sci. 19:137-145. U. S. DEPARTMENT OF COMMERCE, WEATHER BUREAU. 1944. Climatol. Data, California Section. Vol. 48. WATSON, J. R. 1926. Citrus insects and their control. Florida Agric. Exp. Sta. Bull. 183:289-423. Revised.