68 LEAF-CLIMBERS. Chap. IL 



which alone has the power of revolving ; so that they 

 conld be brought only by accident into contact with 

 any neighbouring object. Nevertheless (and this is 

 the remarkable fact) the flower-peduncles, whilst 

 young, exhibit feeble revolving powers, and are slightly 

 sensitive to a touch. Having selected some stems 

 which had firmly clasped a stick by their petioles, 

 and having placed a bell-glass over them, I traced 

 the movements of the young flower-peduncles. The 

 tracing generally formed a short and extremely irre- 

 gular line, with little loops in its course. A young 

 peduncle 1J inch in length was carefully observed 

 during a whole day, and it made four and a half 

 narrow, vertical, irregular, and short ellipses each 

 at an average rate of about 2 hrs. 25 m. An ad- 

 joining peduncle described during the same time 

 similar, though fewer, ellipses. As the plant had 

 occupied for some time exactly the same position, 

 these movements could not be attributed to anv change 

 in the action of the light. Peduncles, old enough for 

 the coloured petals to be just visible, do not move. 

 With respect to irritability,* I rubbed two young 

 peduncles (1J inch in length) a few times very lightly 

 with a thin twig ; one was rubbed on the upper, and 

 the other on the lower side, and they became in 

 between 4 hrs. and 5 hrs. distinctly bowed towards 



* It appears from A. Kerner's when they are rubbed or shaken : 



interesting observations, that the Die Schutzmittel des Pollens 



flower-peduncles of a large number 1873, p. 34. 

 of plants are irritable, and bend 



