TENDRIL-BEARERS. 73 



portion of the main stem is only slightly sensitive. The terminal 

 branches lightly rubbed with a twig did not curve until from 30m. 

 to 42m. had elapsed : they slowly became straight again in between 

 lOh. and 20h. A loop of thread weighing one-eighth of a grain 

 plainly caused the thinner branches to curve, as did occasionally 

 a loop weighing one-sixteenth of a grain ; but this latter slight 

 weight, though left suspended, was not sufficient to cause a per- 



manent flexure. 



tendril 



upper internode together revolve vigorously and quickly, though 

 irregularly, and sw^eep a wide space. The figure traced on a bell- 

 glass was either an irregular spire or a zigzag line. The nearest 

 approach to an ellipse was an elongated figure of 8, with one end 

 a little open ; this was completed in Ih. 53m. During a period of 

 6h. 17m. another shoot made a complex figure, apparently repre- 

 senting three and a half ellipses. "WTien the lower part of the 

 petiole bearing the leaflets was securely fastened, the tendril itself 

 described similar but much smaller figures. 



This species climbs well. The tendrils after clasping a stick 

 become thicker and more rigid ; but the blunt hooks do not turn 

 and adapt themselves to the supporting surface, as is the case in 

 so perfect a manner with some of the Bignoniacese and the Cohcea. 

 In young plants 2 or 3 feet in height, the tendrils, which are only 

 half the length of those borne by the same plants when grown 

 taller, do not contract spirally after clasping a support, but only 

 become slightly flexuous. Tull-sized tendrils, on the other hand, 

 contract spirally, excepting the thick basal portion. Tendrils 

 which have caught nothing simply bend downwards and inwards, 

 like the extremities of the leaves of the Corydalis claviculata. 

 But in all cases the petiole after a time becomes angularly and 

 abruptly bent like that of the Eccremocarpus. 



CtrcuEBiTACE^, — The tendrils in this family have been ranked 

 by several competent judges as modified leaves, stipules, and 

 branches; or the same tendril as part leaf and part branch. De 

 Candolle considers the tendrils in two of the tribes as different 

 in their homological nature*. From facts recently adduced, Mr. 

 Berkeley thinks that Payer's view is the most probable, namely, 

 that the tendril is "a separate portion of the leaf itself "f. 



■ 



* I am indebted to Prof. Oliver for information on this head. In the 

 Bulletin de la Societe Botanique de France, 1857, there are numerous discus- 

 sions on the nature of the tendrils in this family. 



t Gardeners' Chronicle, 1864, p. 721. From the affinity of the Cucurbitace® 

 to the Passifloracea), it might be argued that the tendrils of the former are 



