Page:Life Movements in Plants.djvu/262

232 rhythmic activity of its leaﬂets forulmut ~18 hours, after which there is an arrest of mcvmucnt.

In this statc of suh-tmiicity the zirrcstml autonomous activity is l‘UV'lV'Otl umlcr the acticu of various stimuli. 'l‘hiH tlw inciiluuci- of light on thc pulviuulc initiates pulsa- tcry mcvi-nu-uts, which pvt-sists for :1 timu oven (in illt' ci-ssuticn of stimulus. 'l‘liis pcrsistcnce of autonomous activ- ity incrvuscs with thc inu-usity uuil (lurutinn of stimulus tn which tlu- lvnlli-t llilii lwml subjcctml.

The arrested autmmmcus activity of growth may ut'tcu Im l't'Vth'tl hy the :u-iinu ul' stimulus. Thus the arrested growth in u muturc stylc nr Ilulm'a (ll/m was renewed by clcctric stinmlutiun.