lplant==tooD anD /IBotion 137 



pursuit or bending toward earth is called geotropism, 

 or earth-following. Thus the radicle, or root-part, 

 always grows down into the earth, while the plumule 

 ascends. The poppy is a pronounced sun-follower 

 while it is in bud, and an earth-seeker in blossom 

 and seed-bearing. Note the curvature of poppy 

 stems. 



]Many leaves and stems have some especial way of 

 growing with regard to the horizon, and nothing will 

 induce them to change their fashion. You may 

 turn them, tie them, even nail them fast, and they 

 Avill pull away and go according to their habit. 

 Plants expend a deal of energy in growth movements 

 of various kinds, for nearly all plant motion is a 

 form of growth. 



Gravity, light, heat, moisture, electricity, strength 

 of fibre, sensitiveness of surface, are all parts of the 

 '' how " and the " why " of plant motion. 



You can force a leaf tip or a terminal bud to write 

 for you the story of its motions. Insert a bristle or 

 a cambric needle in the tip of the leaf or bud ; smoke 

 a pane of glass well and lay it where the point 

 of the needle or bristle will just touch the smoked 

 side. As it moves the path of motion will be traced 

 upon the glass. 



Interesting as is the study of plant motion, let us 

 forsake it and consider for a little plant-food. The 



