Nutrition relations to the solid phase of the soil were different and also their relations to the selective absorption of ions by living root cells. Some ions fluctuated in concentration more widely than others. The phosphate ion was present usually in very low concentrations. Potassium fell in an intermediate position. The total amounts of phosphate ions present Sotutioms displaced from cropped (A) soils at beginning and at the end of the growing scasMt {19Z3) and at the beginning of the next grounng season {1924) Lecture 1 9-Survey placed many times in the soil solution, from the solid phase of the soil, and to varying degrees the same was true of other ions. The concept of "supplying DispUced soiuHons ffon Hoa gland-10-Plant Nutrition solution studies were made on many other soils in California and elsewhere, and it has become apparent that soil solutions can often be much more dilute than those of our original set of soils, and still plants will not necessarily fail to absorb adequate amounts of nutrient ions. Thus, the concept of "supplying power" and the interrelation of the solid to the liquid phase of the soil became considerations of paramount significance and they are so today.

IntroductionThe discussion in this paper is based on the assumption that the reader is familiar with earlier work on Valonia, Nitella, and Chara cells (3, 5, 15-17, 23-25, 42), and with the series of recent reports by STEWARD (32-36) and his co-workers (2, 37-40) on accumulation of salts by storage tissues. These latter researches yielded clear evidence that salt accumulation (movement of cations and anions into the vacuole against concentration gradients) by storage tissues is dependent upon the metabolic activities of living cells, reflected in aerobic respiration. It was concluded that capacity for maintained salt accumulation by these tissues is associated with a state of intense cell metabolism characteristic of cell growth and cell division. The problem now to be discussed is that of salt accumulation by roots with particular reference to metabolic processes. This problem has special significance for students of soil and plant interrelations, and at the same time has broad ramifications in the field of general physiology. One of the most fundamental of cell functions is involved.

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