Effects of hypergravity on the elongation and morphology of protonemata of Plant, Elongation growth of protonemata of Adiatitutn capillus-vetieris, which can be controlled by light irradiation, was examined under acropetal and basipetal hypergravity conditions (from -13 to -1-20 g) using a newly developed centrifugation equipment. Elongation of the protonemata under red light was inhibited by basipetal hypergravity at more than -Hi5 , <, ' but was promoted by acropetal hypergravity from -5 to -8 g. Division of the protonemal cells that was induced by white light was inhibited under basipetal hypergravity at -H20 g but was unaffected under acropetal hypergravity al -15 g. Upon exposure to continuous red light for 7 to 8 days, most of Ihe protonemata grew as filamentous cells in the absence of a change in the normal gravitational force (control), but more than half of the protonemal cells were abnormal in terms of shape when maintained under hypergravity at -f20 g.