8 TWINING PLANTS. Chap. I 



possible that the twisting of the axis of the Hop three 

 times should have caused thirty-seven revolutions. 

 Moreover, the revolving movement commenced in the 

 young internode before any twisting of its axis could 

 be detected. The internodes of a young Siphomeris 

 and Lecontea revolved during several days, but became 

 twisted only once round their own axes. The best 

 evidence, however, that the twisting does not cause the 

 revolving movement is afforded by many leaf-climbing 

 and tendril-bearing plants (as Pisum sativum, Echino- 

 cystis lohata, Bignonia capreolata, Eecremocarpus scaler, 

 and with the leaf-climbers, Solanum jasminoides and 

 various species of Clematis), of which the internodes are 

 not twisted, but which, as we shall hereafter see, re- 

 gularly perform revolving movements like those of true 

 twining-plants. Moreover, according to Palm (pp. 30, 

 95) and Mohl (p. 149), and Leon,* internodes may 

 occasionally, and even not very rarely, be found which 

 are twisted in an opposite direction to the other inter- 

 nodes on the same plant, and to the course of their 

 revolutions ; and this, according to Leon (p. 356), is 

 the case with all the internodes of a certain variety of 

 Phaseolus multiflorus. Internodes which have become 

 twisted round their own axes, if they have not ceased 

 to revolve, are still capable of twining round a support, 

 as I have several times observed. 



Mohl has remarked (p. Ill) that when a stem twines 

 round a smooth cylindrical stick, it does not become 



* 'Bull. Bet Soc. de France,' torn. v. 1858, p. 356. 



