THE ASSERTIVE PLANT 5 



for a support ; round and round the stem travels, 

 reaching out farther and farther every time the 

 circle is complete. On a warm day the stem of 

 the Bean goes round at a wonderfully rapid rate. 

 In one case the tip of the shoot traversed a cir- 

 cumference of two feet in a couple of hours, 

 showing that the rate was an inch in five minutes 

 no mean performance for a plant. 



When the circumnutation of the Bean has been 

 fully observed, it is instructive to place a sup- 

 port within reach of the shoot. This should be 

 upright, seeing that as a general rule the twining 

 plants are not able to climb save up a nearly 

 perpendicular object. The attachment to the 

 stick is a matter which is very quickly accom- 

 plished, for a few minutes after the shoot is actually 

 touching the tip commences to curl round. As 

 soon as the hold is securely accomplished, the 

 manner of growth changes into the spiral twining 

 by means of which the stem will advance up 

 the support. This is probably related to, if not 

 identical with, the process of circumnutation. 

 The passage of the Bean shoot up the support 

 is now very rapid, and on a close summer night 

 will be as much as two inches in the twelve hours. 



Next in importance to the twining plants are 

 those which clamber up by means of tendrils. 



