14 HooKER: PHYSIOLOGICAL OBSERVATIONS 
The unbending presents no new features. 
sive stages in the process and comparison with Fic. 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 Fic. 
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 
TasLeE 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 
Fic. 7 shows succes- 
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Fic. 8. A graph representing the reaction shown in Fics. 6 and 7, drawn according to data in TABLE III, 
on the same scale as FIG. 4. 
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 
opin eect eS Jie ‘ 4) "a ee BE ee eee 5 
eRe Wr Aes Eg re a a cat) ae a ema ea. eee, Se i rei ne eae | ae , 
