The role of sulphur in the metabolism of the tomato, and some other plants, was the object of a critical study by NIGHTNGALE et al. (14) in 1932. This work was followed by a succession of three papers by S. V. EATON (8, 9, 10) dealing respectively with soybeans, sunflowers, and black mustard. In each of the foregoing studies, attention was given to the distribution of sulphur between selected plant parts and to the effects of sulphur deficiency on carbohydrate and nitrogen metabolism. A large measure of emphasis was placed by the authors on proteolysis. BEESON (2) has shown by his analyses that the total sulphur in plants tends to approach or may exceed in concentration that of total phosphorus. COOPER and MITCHELL (5) found that cotton plants cultured under various conditions contained an average of 0.28% of sulphur and 0.24% of phosphorus on the dry weight basis. In a few instances (4,12,18), cotton has been shown to respond under field conditions to sulphur fertilization. The fact that ,attention to the sulphur relations in the nutrition of cotton has been somewhat limited finds one explanation in that sulphur is an ingredient in superphosphate as well as in some of the nitrogen and potash fertilizers.The present study of the sulphur nutrition of the cotton plant has tended to follow lines of inquiry similar to those followed by Nightingale et al. and Eaton. In the discussion of the cotton data, differences and similarities are pointed to among the foregoing five plants. The data on cotton include: (1) distribution and forms of sulphur in cotton plants grown on a fertile soil; (2) the effects of sulphur deficiency on growth and mineral accumulation, and (3) the forms and concentrations of sulphur, carbohydrates and nitrogen in plants grown in sand cultures with two and with five levels of sulphate supply. In each experiment, analyses were made before and after the plants had flowered. Consideration is given to the effects of sulphur supply on fruitfulness.