Although glutamine has long been known as a plant constituent (10), the relationship of this amide to the nitrogen metabolism of the plant has seldom been subjected to direct test. The close analogy in chemical structure with asparagine and the similarity of the conditions under which the respective amides are found have led to the view, early expressed by Schulze (6), that glutamine replaces asparagine as the chief amide in many species and fulfills the same functions. This view is shared by Prianischnikow (4) . Schulze regarded the asparagine, which accumulated in the etiolated seedlings of many species, as a secondary product of protein digestion (7, 8, 9), ammonia being the intermediate product. This idea was supported by the experiments of Suzuki (11), who had found that young plants cultured upon solutions that supply nitrogen in the form of ammonium salts greatly increase their store of asparagine. Prianischnikow (5) has shown that asparagine is synthesized in seedlings in response to the advent of ammonia derived from the decomposition of the protein of the cotyledons, the synthesis occurring both in light and in dark in the presence of carbohydrates, but only in light in their absence. He regards the reaction as a provision against the toxic effect of ammonia, the neutral amide being stored in readiness for subsequent syntheses in which nitrogen in readily available form is required. Mothes (3) has found that asparagine fulfills a similar function in mature plants, and the experiments of Vickery, Pucher, Wakeman, and Leavenworth (15) have also shown that amide nitrogen rapidly accumulates in the leaf of the tobacco plant when cultured in water in the dark. In this case the definite correlation that was observed between the dis-