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. — Positive geotropism in 

 a barrigona palm {Colpotkrinax 

 Wrightii). By some accident the 

 palm, when younger, had been bent 

 over. (Photo by the author.) 



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 



