114 ADJUSTMENT TO ENVIRONMENT 



Tendrils behave somewhat similarly. When a tendril 

 comes in contact with a support it may react, according 

 to its nature, by twining about it or pressing its end into 

 firm contact and forming a sucker-like attachment. In 

 some cases, grape for example, as soon as a firm attach- 

 ment hag" been made this itself acts as a stimulus to cause 

 a coiling of the intermediate part of the tendril so as to 



Fio. 24. — Ccotropism of Stoms. These })ean plants were gro\Mi 

 in a pot which was kept riKht-side up until they were al)Out 3 in. 

 high and then placed on its side. Note that tlie stems have promptly 

 l)cnt upward to bring themselves in the line of gravity'. 



draw the main stem into closer relation with the 

 support. 



Adjustment of Leaves is chiefly accomplished by light 

 stimuli. It is easy to demonstrate this experimentally. 

 If a pot tori plant is placed a few feet away from a lighted 

 window and shielded from light from other sources, all 

 its leaves will presently be found facing the window 



