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 to5. 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 
No. of | Original |/*mgth af") amt, of | Relative Length alter! amt. of | Relative 
Segment Length Reaction Growth Amt. Rea hick Growth Amt. 
I 80 80 te) oO 80 (e) ra) 
2 19 20 I 5 20 fe) o 
2 20 21 I 5 21 oO o 
4 16 18 2 13 18 oO ° 
5 37 43 6 16 44 I 2 
6 32 41 9 28 43 2 5 
7 34 44 10 29 49 5 II 
Totial «003.1 S88 ct AOE ele OO 12 275 _ | 8 3 
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- 
