TENDBIL-BEAREltS. 67 



about two hours, aud was ready to act again. As soon as the 

 tendrils begin to grow old their extremities become hooked, and 

 they then appear, with their two or three pairs of branches, an 

 admirable grappling instrument ; but this is not really the case, 

 for at this period the tips have generally quite lost their sensitive- 

 ness ; when hooked on to twigs some were not at all affected, aud 

 others required from 18 h. to 24 h. to clasp the twigs. Ultimately 

 the lateral branches of tho tendril, but not the middle or main 

 stem, contract spirally. 



Lathy rus aphaca. — As the tendril here replaces the whole leaf 

 (except occasionally in very young plants), the leaf itself being 

 replaced in function by the large stipules, it might have been ex- 

 pected that the tendrils would have been highly organized ; this, 

 however, is not so. They aro moderately long, thin, and un- 

 branched, with their tips slightly curved : they are sensitive whilst 

 young on all sides, but chiefly on the coucave side of the extre- 

 mity. They have no spontaneous revolving power, but arc at first 

 inclined upwards at an angle of about 45°, then move into a hori- 

 zontal position, and ultimately bend downwards. The young 

 iuternodes, on the other hand, revolve in ellipses, and carry with 

 them the tendrils : two ellipses were completed, each in nearly 

 5h.; the longer axes of these two, and of some subsequently 

 formed ellipses, were directed at about an angle of 45° from the 

 line of the axis of the previous ellipse. 



Lathyrus yrandijlorus. — The plants observed were young, and 

 not growing vigorously, yet sufficiently so, I think, for my observa- 

 tions to bo trusted. Here we have the rare case of neither inter- 

 nodes nor tendrils having any spontaneous revolving power. The 

 tendrils in vigorous plants are above 4 inches in length, and are 

 often twice divided into three branches; the tips are curved and 

 are sensitive on the concave side ; the lower part of the central stem 

 is hardly at all sensitive. Hence this plant climbs simply by its 

 tendrils being brought, through the growth of the stem, or the more 

 efficient aid of the wind, into contact with surrounding objects, 

 which are then effectually clasped. I may add that the tendrils, or 

 the internodes, or both, of Vicia sativa spontaneously revolve. 



CoMPOSiTiE. — Mutisia clematis. — The enormous family of Com- 

 posite is well known to include very few climbing plants. We 

 have seen in the Table in the first Part that Mikania is a regular 

 twiner, and Mutisia is the only genus, as far as I can learn, which 

 bears tendrils : it is therefore interesting to discover that these 

 tendrils, though rather less metamorphosed from their primordial 



f 2 



