so MOVEMENTS OF PLANTS 



you must bend upwards" ; and when this order has 

 been obeyed the tip says, "It is of no use, I am still 

 horizontal — go on bending." The result is that 

 the stem curls up into a spiral like a corkscrew or 

 a French horn, as shown in Fig. 4. 



Fig. 4. — Seedling Sorghums supported by their tips in horizontal 

 glass tubes. (From the Annals of Botany, December 1899.) 



These unfortunate plants are in the position of 

 a convict on the treadmill ; their movements are, 

 from their own point of view, absolutely ineffectual 

 and meaningless. The results are, however, of 

 some importance from our point of view, since 

 they give clear support to the theory which I have 

 now attempted to place before you, namely, that 

 the percipient region is at the tip of the Setaria 

 seedling, and that by what corresponds to a 

 reflex action, the stimulus perceived by the tip is 

 transmitted to the motor region. 



I should like to add a few words on the question 

 ow far the movement of plants can be placed under 



