130 
THE VEGETATIVE FUNCTIONS OF PLANTS 
tion between the curvature and the tip is parallel to the 
plumb-line. Examination of the ink-marks will show that 
the zone of curvature is the same as the zone of maximum 
FIG. 87. Negative geotropism in 
a barrigona palm (C olpothrinax 
Wrightii). By some accident the 
palm, when younger, had been bent 
over. 
FIG. 88. Mullein (Verbascum 
thapsus) showing geotropic recov- 
ery of the terminal inflorescence, 
after having been bent over. 
growth in length. The stimulus of gravity has modified 
the distribution of the rate of growth in such a way that 
the upper side of the sprout has grown more rapidly than 
the under side. After the sprout has become oriented 
