70 LEAF-CLIMBERS. Chap. II. 



the power of movemeiit has been transferred to the 

 flower-peduncles from the young intemodes, and sensi- 

 tiveness from the young petioles. But to whatever 

 cause these capacities are due, the case is interest- 

 ing ; for, by a little increase in power through natural 

 selection, they might easily have been rendered as 

 useful to the plant in climbing, as a,re the flower- 

 peduncles (hereafter to be described) of Vitis or 

 Cardiospermiun. 



Bhodoohiton voluhile. — ^A long flexible shoot swept a 

 large circle, following the sun, in 5 hrs. 30 m. ; and, as 

 the day became wanner, a second circle was completed 

 in 4 hrs. 10 m. The shoots sometimes make a whole 

 or a half spire round a vertical stick, they then run 

 straight up for a space, and afterwards turn spirally in 

 an opposite direction. The petioles of very young 

 leaves about one-tenth of their full size, are highly 

 sensitive, and bend towards the side which is touched ; 

 but they do not move quickly. One was perceptibly 

 curved in 1 hr. 10 m., after being lightly rubbed, and 

 became considerably curved in 5 hrs. 40 m. ; some 

 others were scarcely curved in 5 hrs. 30 m., but dis- 

 tinctly so in 6 hrs. 30 m. A curvature was perceptible 

 in one petiole in between 4 hrs. 30 m. and 5 hrs., 

 after the suspension of a little loop of string. A 

 loop of fine cotton thread, weighing one sixteenth of a 

 grain (4'05 mg.), not only caused a petiole slowly to 

 bend, but was ultimately so firmly clasped that it 

 could be withdrawn only by some little force. The 

 petioles, when coming into contact with a stick, take 



