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In many plants the potassium contained in the tissues is almost completely water soluble (3,15,16, 18, 19,32) It is generally supposed that much of the potassium present in plants is in the form of salts of organic acids and that these acids and their salts constitute principal components of the buffer systems. A relationship between the total organic acids and the excess of cations over inorganic anions in tobacco leaves of different ages and base composition was shown by PUCHER, VICKERY, and WAKEMAN (22). PIERCE and APPLEMAN (21) grew several species of plants in the same nutrient medium and showed a general correlation between the excess of cations and the total organic acids. In these correlations, however, were ineluded both soluble and insoluble constituents, and variations in insoluble oxalate and calcium contributed much to the variations in the total bases and organic acids. ULRICH (33) has shown that the total organic acid content of sap expressed from barley roots may be varied by unequal absorption of cations and anions from the solution. An absorption of cations in excess of anions results in an in-

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The nature of the carbohydrates of translocation and the reserve carbohydrates in guayule has only recently been elucidated. McRARY and TRAUB (28) isolated a fructosan, tentatively identified as inulin, and HAS- SID et al. (19) definitely characterized this substance as inulin. Later, TRAUB and SLATTERY (41) showed that in addition to inulin, levulins are also present in guayule tissue, and in relatively greater amounts. TRAUB aid SLATTERY (41) also indicated the importance of relating the 89 per cent.ethanol soluble and insoluble levulins to planit functioning. TRAUB, SLAT-TERY and WALTER (42) have shown that the carbohydrates of translocation in guayule are apparently the free reducing sugars since they are always present in relatively small amounts in the roots, stems alnd branches but predominate in the leaves. These workers have also shown that of the total free reducing sugars, the amounts of free nion-fructose sugars are always greater than the amounits of free fructose in spite of the fact that the chief reserve carbohydrates in guayule are polymers of fructose, levulins and inulin. The coniditions of the present experiment were not conducive to large accumulations of inulin, or higher polymer levulins, insofar as the experiment consisted of a phase of rapid growth.So far as the writers are aware, no detailed study has been made of the nitrogenous fractions in guayule.Effects of potassium supply upon growth responses and mineral contents of guayule plants and upon cation and inorganic and organic aniion contents of the leaves have been reported (8,9). In this paper are considered carbohydrate and nitrogenous fractions in tissues of the same plants. Carbohydrate fractionis in plants grown with and without potassium are also reported. MethodsThe miiethods employed in growing the plants have been described (8).