•04 



MECHANICAL LAWS OF GROWTH. 



the circles ; the radius of this circle is recorded in the following table as the radius 

 of curvature. The internode was then left to itself, and its permanent curvature 

 determined in the same manner. The branch was then bent on the other side, and 

 so on, as shown by the table. The internode was finally laid with its concave side 

 on the measuring rod and pressed straight on to it. 



1. Bent . . . , 



2. Bent in opposite direct 

 Straightened 



Heracleum sihiriciim ; stalk of 

 umbel. Before bending 



1. Bent . . . . 



2. Bent in opposite direct 



3. Bent as in (1) 



4. Bent as in (2) 

 Straightened 



Vitisvinifera ; young internode, 

 Before bending . 



1. Bent . 



2. Bent in opposite direct 



3. Bent as in (1) 



4. Bent as in (2) 

 Straightened 



Vitis vi?ii/era; older internode 

 Before bending . 



1. Bent . 



2. Bent in opposite direct 



3. Bent as in (i) 



4. Bent as in (2) 

 Straio:htened 



165-5 



1 6.= 



167-0 



47'5 



47-5 



133-8 



133-0 



19 



22 



5-8 



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 



