ON Drosera rotundifolia 



19 



greatest in the lowest segment and decreased apically. The 

 second reaction was produced the day following the first. The 

 reaction time was i minute, 30 seconds. Growth occurred in 

 Segments 3 to 5. Segment 2 had stopped growing. The third 

 reaction took place two days after the first one. More than an 

 hour elapsed before movement was detected. Growth was con- 

 fined to Segments 4 and 5. No elongation of Segments 2 and 3 

 took place. The third unbending of the tentacle was exceedingly 

 slow, and the pedicel did not regain its original position until 

 three days after stimulation. A fourth reaction could not be 

 induced. The elongations accompanying the first, second and 

 third inflexions were nearly constant, being 0.16 mm., 0.18 mm. 

 and 0.14 mm., respectively. 



Table IX 



Table IX gives the growth during two successive reactions 

 of a tentacle. The growing region is much more restricted in the 

 second than in the first bending. In both cases the rate of growth 

 increases toward the base of the pedicel. 



(d) Discussion 



i. Bending 



The bending of a Drosera tentacle is produced by an accelera- 

 tion of the rate of growth, which extends from the convex side 

 through the middle of the tentacle. In some cases the concave 

 side is likewise included, so that the entire cross-section of the 

 pedicel participates. In other cases the region of accelerated 

 growth stops at a so-called neutral line, somewhere between the 

 middle and the concave side. Under such circumstances the con- 



