14 



Hooker: Physiological observations 



:^E 



-i: 



The unbending presents no new features. Fig. 7 shows succes- 

 sive stages in the process and comparison with Fig. 6 emphasizes 

 the different configuration of the 

 bending and unbending tentacle. 

 The tentacle grew from 2.54 

 mm. to 2.77 mm., an increase 

 of 0.23 mm. 



The reaction is plotted in FiG. 

 8. The complete reaction took 

 39 hours and 15 minutes, an un- 

 usually long time. This experi- 

 ment is perhaps more representa- 

 tive than the first in that growth 

 was confined to the lower half of 

 the pedicel. 



After a day's rest, the tentacle 

 used in the first experiment was 

 stimulated a second time. The 

 leaf was still fresh and actively 

 secreting. At the beginning of 

 this experiment the tentacle 

 measured 3.37 mm. The results 

 of the reaction are shown in 

 Table IV, and are represented 

 in graphical form in Fig. 9. 

 Movement began within two min- 

 utes. The bending was produced 

 by elongation of the abaxial 

 side beginning in Segment 6 and 

 extending apically to Segments 

 5 and 4, and basally to a part of 

 Segment 7. The region of elon- 

 gation and curvature was shorter 

 than in the first reaction, where it 

 included Segments 3 and 2. The 

 acceleration of the rate of growth was also less than during the 

 first inflexion. The time required for the bending was increased 

 to four hours. The time taken to regain the original position was 



