358 



MODIFIED CIBCJUMNUTATION. 



Chap. VU. 



Circiimnutation. — The circumnutating movements of four 

 yoimg shoots were observed during 5 h. 15 m. ; and in this time 

 each completed an oval figure of small size. The main petiole 

 also circumnutates rapidly, for in the course of 31 m. (temp, 

 91° F.) it changed its course by as much as a rectangle six times, 

 describing a figure which apparently, represented two ellipses. 



Fig. 149. 



Vesmodium gyrans: A, stem during the day ; B, stem with leaves asleep. 

 Copied from a photograph ; figures reduced. 



The movement of the terminal leaflet by means of its sub- 

 petiole or pulvinus is quite as rapid, or even more so, than that 

 of the main petiole, and has much greater amplitude. Pfeffer 

 has peen* these leaflets move through an angle of 8° in the 

 course of from 10 to 30 seconds. 



A fine, nearly full-grown leaf on a young plant, 8 inches in 

 height, with the stem secured to a stick at the base of the leaf, 

 •vas observed from 8.30 a.m. June 22nd to 8 a.m. June 24th 



• ' Die Period. Beweg.,' p. 35. 



