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Spring wheat of the Marquis variety was germinated on a net as described by SHIVE (I5). Seedlings carefully selected for uniformity of size and vigor were transferred, when about 5 cm. tall, to SHIVE'S three-salt solution R5C2, after having been mounted in the double piece paraffined cork stoppers devised by TOTTINGHAM (i8). The stoppers were of the proper size to fit quart fruit jars of colorless glass, which were used for culture vessels. Three seedlings were included in each culture. The cultures thus prepared were conducted during a time period of twenty-five days, with renewal of solutions every three or four days. When the seedlings were approximately thirty days old from the time of germination, cultures were selected in which the plants were about equal with respect to size and vigor in so far as this could be judged from careful observation. The plants of the selected cultures, without being removed from the cork stoppers in which they were mounted, were then taken from the three-salt solutions, the roots were washed by carefully dipping them several times into distilled water, allowed to drain, and were then placed in the nutrient solutions devised by the various authors. The glass jars to which the plants were transferred were like those from which they were removed. Each jar had a capacity of goo cc. The formulae of the nutrient solutions devised by the various authors are given in tables I and II in terms of gram-molecules per liter. The solutions made up according to the formulae in table I were corrected to a total osmotic concentration value of approximately I.75 atmospheres by the method of the freezing point lowering, while those prepared according to the formulae in table II were similarly corrected to an approximate osmotic concentration value of i.oo atmosphere. No iron was added to any of these solutions, except to those for which this element is mentioned in the formulae. The solutions devised by BIRNER and LUCANUS (I), CRONE (2), and SACHS (Ii) contained precipitates. In making the

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