SUMMARYThe effect of an interruption of the aeration in the root medium on distribution of dry matter, sugar content and starch content in the roots and the hypocotyl of seedlings ofPhaseolus vulgariswas investigated. The interruption resulted in a shift in the distribution of dry matter from roots to hypocotyl, a higher sugar content in roots and hypocotyl and a lower starch content in the distal part of the root. Restoration of aeration after one day resulted in renewed root growth and decreased sugar contents of the hypocotyl and the roots. Accumulation of starch within the hypocotyl continued. Inhibition of root growth was not caused by a deficiency of assimilates in the roots.