2 MR. DAUWIN ON CLIMBIKG PLATS'TS. 



memoirs by Dutrocliet*. Nevertheless I believe that my obser- 

 vations, founded on tlie close examination of above a hundred 

 widely distinct living plants, contain sufficient novelty to justify 

 me in laying them before the Society. 



Climbing plants may be conveniently divided into those -which 

 spirally twine round a support, those which ascend by the move- 

 ment of the foot-stalks or tips of their leaves, and those which 

 ascend by true tendrils, — these tendrils being either modified 

 leaves or flower-peduncles, or perhaps branches'. But these sub- 

 divisions, as we shall see, nearly all graduate into each other. 

 There are two other distinct classes of climbing-plants, namely 

 those furnished with hooks and those with rootlets ; but, as such 

 plants exhibit no special movements, we are but little concerned 

 mththem; and generally, when I speak of climbing plants, I refer 

 exclusively to the first great class. 



Part I. — Spieally twinikg Pla^^ts. 



This 



dial and simplest condition of the class. My observations will be 

 best given by taking a few special cases. When the shoot of a 

 Hop {Hvmulus Lupulus) rises from the ground, the tw^o or three 

 first-formed internodes are straight and remain stationary ; but 

 the next-formed, whilst very young, may be seen to bend to one 

 side and to travel slowly round towards all points of the compass, 

 moving, like the hands of a watch^ with the sun. , The movement 

 verv soon acouires its full ordinarv^ velocitv- Erom seven obser- 



durin 



and 



d 



for each revolution; and none of the revolutions varied much 

 from this ratp. The revolving movement continues as long fts 

 the plant continues to grow ; but each separate intemode, as it 

 grows old, ceases to move. 



To ascertain more precisely what amount of movement each in- 

 temode underwent, I kept a potted plant in a well-warmed room 

 to which I was confined during the night and day. A long in- 

 clined shoot projected beyond the upper end of the supporting 



— -^^^ 



Treatit^e was published only a few weeks before Mohl's. See also 'The Tege- 

 table Cell ' (translated by Heiifrey), by H. von Mohl, p. 147 to end. 



* "Pes Mouvemeiits ivvolutifs spontanea," &e., * Comptcs Eendus,' torn, xvii- 

 (1843) p. 989 ; "Eecherches sur la Tolubilite desi Tigc&," &c., torn. xk. (1844) 



p. 295» 





