2)8 Field, Forest, and Wayside Flowers 



"The first purpose of the spontaneous revolv- 

 ing movement," says Darwin, "is to enable the 

 shoot to find its support. This is admirably ef- 



Bind-weed (Con-volvulus). 

 Twining " against the sun." 



Hop-vine (Humulus Lupulus). 

 Twining " with the sun. 1 ' 



FIG. 66. Bind-weed and hop-vine. 

 (From the Vegetable World.) 



fected by the revolutions carried on night and 

 day, a wider and wider circle being swept as the 

 shoot increases in length. This movement like- 



