30 MB. DAKWIN ON CLIMBING PLANTS. 



gular line was generally formed; but one day, in the course of 

 eight hours and three quarters, the figure traced, clearly repre- 

 sented three and a half irregular ellipses, the most perfect one of 

 which was completed in 2 h. 35 m. The two opposite leaves moved 

 quite independently of each other. This movement would aid 

 that of the internodes in bringing the petioles into contact with 

 surrounding objects. I discovered this spontaneous movement 

 too late to be enabled to observe the leaves in all the other spe- 

 cies ; but from analogy I can hardly doubt that the leaves of at 

 least C. viticella^ Cfiawmula^ and (7. vitalha move spontaneously; 

 and, judging from C Sieholdi^ this probably is the case with C. 

 montana and G. calycina, I ascertained that the simple leaves of 

 C. glandulosa exhibited no spontaneous revolving movement. 



Clematis viticella, var. venosa, — In this and tbe 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 

 revolving movement, though restricted, is not lost. In our pre- 

 sent species a young internode, placed in front of a window, made 

 three narrow ellipses, transversely to the light, at an average rate 

 of 2 h. 40 m. ; when placed so that the movement was to and fron) 

 the light, the rate was greatly accelerated and retarded, as in the 

 case of twining plants. The ellipses were small ; the longer dia- 

 meter, described by the apex of a shoot bearing a pair of not ex- 

 panded leaves, being only 4-| inches, and that by the apex of the 

 penultimate internode only 1-^ 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 movement of the whole shoot by the 

 wind and by its rapid growth would probably be almost equally 

 efiB.cient with the spontaneous movements in bringing the petioles 

 into contact with surrounding objects. 



The leaves are of large size. There are three pairs of lateral 

 leaflets and a terminal one, all borne by rather long petioles. The 

 main petiole bends a little angularly downwards at each point 

 where a pair of leaflets arises, and the petiole of the terminal 

 leaflet is bent downwards at right angles ; hence the whole petiole, 

 with its rectangularly bent extremity, acts as a hook. This, 

 with the lateral petioles directed a little upwards, forms an ex- 

 cellent grappling apparatus by which the leaves readily become 

 entangled with surrounding objects. If they catch nothing, the 



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