12 HooKER: PHYSIOLOGICAL OBSERVATIONS 
5. Before the experiment it measured 2.7 mm. The reaction 
is in all essential respects similar to the previous example, but 
there are important differences. The tentacle was on a mature 
leaf. It had not, however, been stimulated before the experiment. 
Bending was produced by an elongation of the convex side and the 
median section, accompanied by contraction of the concave side. 
The increase in length on the abaxial side was twice as great as the 
contraction of the adaxial side. The ultimate stage of bending 
was reached 5 hours and 45 minutes after stimulation. Unbending 
was caused by gradual growth on the concave side and in the 
median section together with slight contraction of the convex side. 
The original position was reached after 23 hours and 30 minutes. 
The tentacle then measured 2.83 mm. It had grown 0.13 mm. 
during the experiment. 
A third example is given in TABLE III. This tentacle was in 
TABLE III 
No. of 3-45 | Bee | oe Fo ake aot 4.05 | 9.20 | 4.00 g-00 
i Segment | P. M.| P. M.| P. M.| P. M.| P. M |P M.| A. M.| P M. ACM. 
| 
o I 84 | 84 84 84 | 84/| 84] 84] 84 84 
gy 2 $7} $7.1 58 1 SB | SB Sh) 58) 681 58 
a= 3 37 | 37 | 37) 37 | 40 | Bt Pas) 4a | 43 
a 4 St) Blo Sh) 344: 420) as 4s) a3 i 8 
s | 45| 47| sa] 53| 57| s7| 54| so | 49 
Total...| 254 | 256 | 263 | 266 | 279 | 283 | 281 | 278 277 
=o I 82 | 82 | 82} 82) 82 | 82) 82 | 82 | 82 
Eis 2 SP 1°57 137) S77 87) 87 | 58 | sot Ot 
| | 
8% 3 58 SS.) 58158) 504 504. Go | 69 1 06 
2 4 46 | 46| 42| 37| 37| 40] 42| 42| 42 
5 12 | 43 41- 4$2-]) 48.) 32.) 421 ag | 33) 9a 
; ) } } } 
| | r | | 
oy i Total. . | 255 | 255 | 251 | 246 | 247 | 250 | 265 | 268 | 275_ 
the third row from the outside, on a leaf in excellent condition. 
It reacted with great rapidity. Movement was detected within 
a minute after stimulation, and the bending was completed in 
twenty minutes. The table shows clearly that elongation com- 
menced in Segment 5, the most basal portion of the abaxial side; 
after ten minutes Segment 4 likewise increased in length; and 
after three minutes more Segment 3 began to grow. The drawings 
in Fic. 6 show the bending, and illustrate the apical progress of 
the reaction. As in the previous case, the bending was produced 
