THE WORK OF STEMS 273 



A part of the shoot may be brought indoors and 

 placed with the cut end in water, while a stream of 

 water from the faucet is directed on it. Do you see 

 any advantage in this behavior of tendrils ? Does 

 the part of the tendril between the stem and the 

 support coil ; if so, in what direction ? Do you see* 

 any advantage in this coiling ? Do the tendrils which 

 find support grow stronger and more woody than 

 those which do not 1 What is the advantage of this ? 

 Why does the tendril coil? The best answer we 

 can give to this question at present is that contact 

 with a solid body arrests the growth of the contact 

 side and promotes that of the opposite side. Why 

 this is so we do not know. If we imitate the coiling of 

 a tendril by cutting out a strip three or four inches 



152. Behavior of a strip of flower-stalk of Dandelion, fastened at both ends and 

 immersed in water (to show the reversal of coiling which occurs in tendrils). 



long from a Dandelion stalk (Fig. 152) and fastening 

 the two ends by clothes-pins, we find on putting it in 

 water that it shows the same reversal of the coils 

 which is shown by a tendril which has fastened itself 

 to a support ; it would seem that the reversal of the 

 direction of the coiling is due to purely mechanical 

 reasons, since the same result can be gotten with a 

 twisted string. 

 B 



