GENERAL PROPERTIES OF GROWING PARTS OF PLANTS. 
785. 
Name. 
3. Bent as in (i) 
4. Bent as in (2) 
Straightened 
Fitis 'vinifera; young internode 
Before bending . 
1. Bent ... 
2. Bent in opposite direct 
3. Bent as in (i) 
4. Bent as in (2) 
Straightened 
Fitis 'vinifera ; older internode 
Before bending . 
1. Bent . 
2. Bent in opposite direct 
3. Bent as in (i) 
4. Bent as in (2) 
Straightened 
Length of the 
internode. 
167*0 
47*5 
47-5 
133-8 
133-0 
curvature 
when bent. 
Radius of cur- 
vature when 
left to itself. 
25 
22 
Thickness of 
the middle part 
of the internode. 
8 
17 
1 1 
25 
These examples, selected from a long series of observations, show: — (i) that 
growing internodes are very flexible, (2) that after bending they do not altogether 
recover their straightness, or that the elasticity of curvature is imperfect; (3) that 
repeated bendings constantly in opposite directions leave progressively smaller curva- 
tures^; (4) that one vigorous bending, and to a still greater extent repeated ones 
in opposite directions, leave the internode flaccid, or deprive it of its rigidity (of 
which no special account is taken in the table) ; and (5) in the case of the three first 
examples, that an internode bent first in one and then in another direction lengthens 
slightly, while in the case of the two last there was no lengthening, but in one even 
a perceptible contraction. 
(c) Change of length of the concave and convex sides of a bent internode. Here 
again, as in paragraph ^, the bending was done by the hands, and measured by the 
radius of curvature on a card on which concentric circles were drawn. The original 
length, as well as those of the sides which remain concave and convex after the object 
is left to itself, were measured by means of a carefully applied strip of card divided 
into millimetres. In order to get a great difference between the concave and convex 
sides, very thick internodes were selected, and their thickness measured in the 
middle. 
Name. 
Silphium perfoliatum 
13*2 mm. thick. 
Before bending 
Bent 
Bent in opposite direct. 
Straightened . 
Ligularia macrophylla 
7*5 mm. thick. 
Before bending 
Bent 
Bent again 
Bent in opposite direct. 
Length of 
internode. 
85 mm. 
Radius of 
curvature 
when bent. 
14 cm. 
14 
Radius of 
curvature 
' when left 
to itself. 
26 cm. 
30 
Contraction 
of the 
concave side. 
I mm. 
I 
Lengthening 
of the 
convex side. 
2 mm. 
i'5 
85 
199 
6 
17 
3*5 
4 
5 
13 
3*5 
4'5 
6 
30 
•5 
1*5 
The curvature is less the greater the radius of curvature. 
3 E 
