Cuar. I. TWINING PLANTS. 33 
Species of the same genus move at different rates. 
The rate does not seem governed by the thickness of 
the shoots: those of the Sodlya are as thin and flexible 
as string, but move more slowly than the thick and 
fleshy shoots of the Ruseus, which seem little fitted for 
movement of any kind. The shoots of the Wistaria, 
which become woody, move faster than those of the 
herbaceous Ipomeea or Thunbergia. 
We know that the internodes, whilst still very 
young, do not acquire their proper rate of movement ; 
hence the several shoots on the same plant may some- 
times be seen revolving at different rates. The two or 
three, or even more, internodes which are first formed 
above the cotyledons, or above the root-stock of a 
perennial plant, do not move; they can support them- 
selves, and nothing superfluous is granted. 
A greater number of twiners revolve in a course 
opposed to that of the sun, or to the hands of a watch, 
than in the reversed course, and, consequently, the 
majority, as is well known, ascend their supports from 
left to right. Occasionally, though rarely, plants of 
the same order twine in opposite directions, of which 
Mohl (p. 125) gives a case in the Leguminose, and we 
have in the table another in the Acanthacee. I have 
seen no instance of two species of the same genus 
twining in opposite directions, and such cases must be 
rare; but Fritz Miller * states that although Mikania 
* Journal of the Linn. Soc. interesting paper, in which he 
(Bot.) vol. ix. p. 344. I shall corrects or confirms various state- 
have occasion often to quote this ments made by me. 
