Intaot Lepidium sativum seedling roots, Avena sativa coleoptiles, Phyo0mYces blakesleeanus sporangiophores and exoised Triticum vulgare nodes.were placed with their long exes pel'pend1cular to a magnetio gradient and transverse to the lines or magnetio toroe, under conditions eliminating geotropic ourvatures and under controlled environmental oonditions. A permanent magnet of maximum field strength 4,000 oe and maximum gradient 5,600 ce/om was used tor experiments with the tour speoies. The experiments with Avena sativa ooleoptiles and PpycomYces blakesleeanus aporangiophores were repeated using a permanent magnet or ,maximum tield strength 7,100 oe and ot maximum gradient 8,000 Ce/em. The Lepidium sativum roota, the Avena sativa ooleoptiles and Pgyoom,oes blakesleeanua (atage I sporangiophores only) grew and ourved in a direotion whioh was down the magnetio gradient. Tho stage II-III and stage IVa sporang1ophores did not ourve magnetotrop1oally, neither did the Triticum vulsare nodes. Control plants did not ourve and evidence is g1ven that the statist10ally s1gnifioant magnetotrop1c ourvatures were in response to the stimUlus of the non-uniform magnetio field. The reoiprocal of the 1!R1dium sat1vum root's magnetotrop10 reaotion time was a function ot the magnetio field (P • 0.02) and the paramagnetic force (P • 0.001) aoting on the root at the start of the experiment. For Phyo0ml0es blakesleeanus stage I sporangiophores, both the reoiprocal or the reaotion time and the maximum angle or curvature attained within 2.5 hours were individually statistically signifioant tunotions ot (a) the magnetio field strength (b) the magnetio gradient and (0) the paramagnetio toroe acting on the sporangiophore initially. ~e ourvature rate was a significant runction ot the magnetio field strength and the paramagnetic torce aoting on the sporangiophore initiall,.. There was no evidenoe that the magnetotrop10 ourvatures or Lep1dium aatlvum and Avena sativa were caused by a migration of amyloplasta in the non-uniform magnetic field. ExPeriments testing other poas1ble mechanisms or magnetotropio curvatures are disoussed.