CHAPTER VIII. 



FURTHER EXPERIMENTS ON MOVEMENT. 



Section A. Stimulus of contact, cJiemical agency, mois- 

 ture, cha/nges in illumination and in 

 temperatwre. 



Section B. Autonomous m,ovements : Periodicity. 



Section A. Stimulus of Contact, &c. 



(230) .Tendrils: sensitive to contact. 



Among the most sensitive of tendrils are those of 

 Sicyos . angulatus, Passiflora gracilis and Echinocystis 

 lobata : the common Bryony {Bryonia dioica) is however 

 more generally accessible, and being a native plant 

 requires in ordinary summer weather no special arrange- 

 ment with regard to temperature. Avoid the very young 

 tendiils and select one with a slight hook at the end. 

 With a pencil or rod rub the inside of the terminal part 

 of the tendril for a minute. It will almost at once show 

 signs of curvature, and will be strongly curved in 

 2 minutes, — so that for instance the terminal 15 mm. 

 form a complete ring of 3 or 4 mm. in diameter. 



