Chap. HI. BIGNONIACE^. 91 



a second in 2 hrs. oo m. By these combined move- 

 ments of the internodes, petioles, and grapnel-like 

 tendrils, the latter are soon brought into contact with 

 surrounding objects. When a shoot stands near an 

 upright stick, it twines regularly and spirally round 

 it. As it ascends, it seizes the stick with one of its 

 tendrils, and, if the stick be thin, the right- and left- 

 hand tendrils are alternately used. This alternation 

 follows from the stem necessarily taking one twist 

 round its own axis for each completed circle. 



The tendrils contract spirally a short time after 

 catching any object ; those which catch nothing merely 

 bend slowly downwards. But the whole subject of 

 the spiral contraction of tendrils will be discussed 

 after all the tendril-bearing species have been de- 

 scribed. 



Bignonia littoralis. The young internodes revolve 

 in large ellipses. An internode bearing immature 

 tendrils made two revolutions, each in 3 hrs. 50 m. ; 

 but when grown older with the tendrils mature, it 

 made two ellipses, each at the rate of 2 hrs. 44 m. 

 This species, unlike the preceding, is incapable of 

 twining round a stick : this does not appear to be 

 due to any want of flexibility in the internodes or 

 to the action of the tendrils, and certainly not to 

 any want of the revolving power ; nor can I account 

 for the fact. Nevertheless the plant readily ascends 

 a thin upright stick by seizing a point above with its 

 two opposite tendrils, which then contract spirally. If 

 the tendrils seize nothing, they do not become spiral, 



