124 TENDKIL-BEAKERS. Chap. III. 



petioles (/ to I) doing several days, produced no 

 effect. Yet the three petioles f, g, and h were not 

 quite insensible, for when left in contact with a stick 

 for a day or two they slowly curled round it. Thus 

 the sensibility of the petiole gradually diminishes 

 from the tendril-like extremity to the base. The in- 

 ternodes of the stem are not at all sensitive, which 

 makes Mold's statement that they are sometimes con- 

 verted into tendrils the more surprising, not to say 

 improbable. 



The whole leaf, whilst young and sensitive, stands 

 almost vertically upwards, as we have seen to be the 

 case with many tendrils. It is in continual move- 

 ment, and one that I observed swept at an average 

 rate of about 2 hrs. for each revolution, large, though 

 irregular, ellipses, which were sometimes narrow, 

 sometimes broad, with their longer axes directed to 

 different points of the compass. The young inter- 

 nodes, likewise revolved irregularly in ellipses or 

 spires ; so that by these combined movements a con- 

 siderable space was swept for a support. If the terminal 

 and attenuated portion of a petiole fails to seize any 

 object, it ultimately bends downwards and inwards, 

 and soon loses all irritability and power of movement. 

 This bending down differs much in nature from that 

 which occurs with the extremities of the young leaves 

 in many species of Clematis; for these, when thus 

 bent downwards or hooked, first acquire their full 

 degree of sensitiveness. 



Dicentra thalidrifolia. In this allied plant the 



