Abstract
LiCl inhibits the nyctinastic closure of folioles of excised leaves and enhances their opening, if there are 3 h before the light is switched off or on; the minimal concentration for significant effects on closure is 3·10-4 M, and on opening 3·10-3. The use of chlorides of other cations and other Li salts showed specificity of the lithium for the closure movement, the effect being reversed by KCl and NaCl. For the opening movement the Li effect is less specific. These results are compared to those obtained in other phenomena.