LEAF-CLIM13EKS. 39 



fully to examine them. They never act as tendrils : I repeatedly 

 placed thin sticks in contact with young and old peduncles, and 

 I allowed nine vigorous plants to grow over an entangled mass of 

 branches ; but in no one instance did a peduncle bend round any 

 object. It is indeed in the highest degree improbable that this 

 should occur, for the flower-peduncles are generally developed on 

 branches which have already securely clasped a support by their 

 petioles ; and when borne on free depending branches, they are 

 not produced by the terminal portion of the internode which 

 alone has the power of revolving ; so that they can only acci- 

 dentally and rarely be brought into contact with any surrounding 

 object. Nevertheless (and this is the remarkable fact) these flower- 

 peduncles, whilst young, exhibit feeble revolving powers, and are 

 slightly sensitive to a touch. I selected some stems which had 

 firmly clasped a stick by their petioles, and, placing a bell-glass 

 over them, traced the movements of the young flower-peduncle?^. 

 Some days these moved over a short and extremely irregular line, 



iiaking 



One day a young peduncle 

 Fullv observed, and it made 



four and a half narrow, vertical, irregular, and very short 

 ellipses — each at an average rate of about 2 h. 25 m. ; an adjoining 

 peduncle described during the same time similar,but fewer, ellipses. 

 As the plant had for some time occupied exactly the same position, 

 these movements could not be attributed to the varying action of 

 the light. *■ Peduncles, old enough for the coloured petals to be 

 just visible, do not move. With respect to irritability, I rubbed 

 a few times very lightly with a thin twig two young peduncles (1^ 

 inch in length), one on the upper side and the other on the 

 lower side, and they became in between 4 h. and 5 h. plainly bowed 

 towards the rubbed sides ; in 24 h. subsequently, they straightened 

 themselves, Next day they were rubbed on the opposite sides, 

 and they became perceptibly curved towards these sides. Two 

 other and younger peduncles (three-fourths of an inch in length) 

 were lightly rubbed on their adjoining sides, and they became so 

 much bowed towards each other, that the arcs of the bows stood 

 at nearly right angles to their previous positions ; this was the 

 greatest movement seen by me ; subsequently tliey straightened 

 themselves. Other peduncles, so young as to be only three-tenths 

 of an inch in length, became curved when rubbed. On the 

 other hand, peduncles above 1| inch in length required to be 

 rubbed two or three times, and then became only just percep- 



tibly curved. 



peduncles 



