TEND1UL-BEARERS. 91 



the sun, in 3 h. 5 m., 2 h. 40 in., and 2 h. 50 m. ; perhaps it 

 might have travelled more quickly when nearly full-grown. The 

 plant was placed in front of a window, and I ascertained that, 

 as with twining stems so with these tendrils, the light accelerated 

 the movement in one direction and retarded it in the other, 

 the semicircle towards the light heing performed in one instance 

 in 15 m., and in a second instance in 20 m. less time than that 

 required by the semicircle towards the dark end of the room. 

 Considering the extreme tenuity of these tendrils, the action of 

 the light on them is remarkable. The tendrils are long, and, as 

 just stated, very thin, with the tip slightly curved or hooked. 

 The concave side is extremely sensitive to a touch — even a single 

 touch causing it to curl inwards ; it subsequently straightens 

 itself, and is again ready to act. A loop of soft thread weighing 

 -jlj-th of a grain caused the extreme tip to bend ; at another time I 

 tried to hang the same little loop on an inclined tendril, but three 

 times it slid off; yet this extraordinarily slight degree of fric- 

 tion sufficed to make the tip curl. The tendril, though so sensi- 

 tive, does not move very quickly after a touch, no conspicuous 

 change being observable until 5 or 10 m. had elapsed. The con- 

 vex side of the tip is not sensitive to a touch or to a suspended 

 loop of thread. In one instance I observed a tendril revolving 

 with the convex side of the tip forwards, and on coming into con- 

 tact with a stick it merely scraped up and past the obstacle and 

 was not able to clasp it; whereas tendrils revolving with the 

 concave side of their tips forward promptly seize any object in 

 their path. 



Passiflora quadrangularis. — This is a very distinct species. 

 The tendrils are thick, long, and stiff; they are sensitive to a 

 touch only towards the extremity and on the concave surface. 

 When a stick was so placed that the middle of the tendril came 

 into contact with it, no curvature ensued. In the hothouse a 

 tendril made two revolutions each in 2 h. 22 m. ; in my cooler 

 study one was completed in 3 h., and a second in 4 h. The inter- 

 nodes do not revolve; nor do those of the hybrid P.Jloribunda. 



Tacsonia manicata. — Here again the internodes do not revolve. 

 The tendrils are moderately thin and long ; one made a narrow 

 ellipse in 5 h. 20 m., and the next day a broad ellipse in 5 h. 7 m. 

 The extremity being lightly rubbed on the concave surface, be- 

 came just perceptibly curved in 7 m., clearly curved in 10 m., and 

 hooked in 20 m. 



"We have seen that the tendrils in the last three families, namely 



