Chap. II. CLEMATIS. 53 



G. montana and G cahjcina. I ascertained that the 

 simple leaves of G. glandulosa exhibited no sponta- 

 neous revolving movement. 



Clematis viticella, var. venosa. In this and the two 

 following species the power of spirally twining is 

 completely lost, and this seems due to the lessened 

 flexibility of the internodes and to the interference 

 caused by the large size of the leaves. But the re- 

 volving movement, though restricted, is not lost. In 

 our present species a young internode, placed in front 

 of a window, made three narrow ellipses, transversely 

 to the direction of the light, at an average rate of 

 2 hrs. 40 m. When placed so that the movements were 

 to and from the light, the rate was greatly accelerated 

 in one half of the course, and retarded in the other, as 

 with twining plants. The ellipses were small ; the 

 longer diameter, described by the apex of a shoot 

 bearing a pair of not expanded leaves, was only 4 J 

 inches, and that by the apex of the penultimate inter- 

 node only 1J inch. At the most favourable period of 

 growth each leaf would hardly be carried to and fro 

 by the movement of the internodes more than two or 

 three inches, but, as above stated, it is probable that 

 the leaves themselves move spontaneously. The move- 

 ment of the whole shoot by the wind and by its rapid 

 growth, would probably be almost equally efficient as 

 these spontaneous movements, in bringing the petioles 

 into contact with surrounding objects. 



The leaves are of large size. Each bears three pairs 

 of lateral leaflets and a terminal one, all supported on 



