140 



RELATIONS OF PLANTS TO LIGHT 



the photolytic movements of chloroplasts in exposed cells, para- 

 phototropic reactions, and photeolic, or nyctitropic movements 



Fig. 71. Lactuca scariola (compass plant), seen from east or west. The leaves 

 have been moved by curvatures and torsions until the laminae are directed approxi- 

 mately north and south to within a few degrees. After Atkinson. 



of leaves. The chloroplasts of a large number of species move 

 toward the walls parallel to the surface of the leaf in diffuse light, 



