The simultaneous movement of two ions in the phloem of the Saxifraga stolon.

Paris of tracers were applied simultaneously to the long thin stolons of Saxifraga sarmentosa. After several hours of translocation the very precise pattern of exponential fall-off was examined and interpreted in the light of a model of mass flow with leakage. (42)K appears to leak faster than (22)Na; (86)Rb is very close to (42)K. The anion (82)Br shows a lower fall-off than (137)Cs; this is tentatively regarded as due to a much-reduced leakage, though it might imply a higher velocity. The implications of these findings for sieve-tube mechanism are uncertain.