Abstract
An apparatus is described by means of which Lemna perpusilla 6746 was grown photoautotrophically at a series of constant concentrations of inorganic sulfate, as low as 0.26 mum. Theoretical considerations relevant to this system are discussed and examples of the operation of the apparatus are presented. The data obtained were used to calculate sulfate uptake by the plant colonies as a function of sulfate concentration. The apparatus should be useful for the production of relatively large quantities of Lemna, grown under highly uniform conditions, with or without limitation of one or more nutrient(s). Other small vegetatively reproducing aquatic plants could be similarly studied. Uptake studies could be carried out on a variety of plant materials.