J9o FREAKS OF PLANT LIFE. 



By observing the older stems of the hop which 

 have become entwined round a support, or, better 

 still, taking a piece of old hop-bine a few inches in 

 length and splitting it down longitudinally with a 

 knife, we shall observe that the stem is also twisted 

 upon itself; that, in addition to twisting round its 

 support, it twists round its own axis. Mr. Darwin 

 has shown that an internode 9 inches long, and 

 which had revolved thirty-seven times, had become 

 three times twisted round its own axis in the line of 

 the course of the sun. Some have thought in past 

 times that the twisting of the stem caused the rota- 

 tion, but it is hardly possible that three twists in the 

 stem should have caused thirty-seven rotations. 

 Many twining plants twist in this manner round 

 their own axis. Experiments have demonstrated 

 that when the plant climbs round a smooth support, 

 such as a glass rod, it is much less twisted on itself 

 than when twining round a rough or rugged support. 

 The axial twisting bears some relationship, therefore, 

 to inequalities in the support, as well as to revolving 

 freely without support. Internodes may be observed 

 rotating freely before they have acquired a single 

 twist on their own axis. The axial twisting must, 

 therefore, have some other cause or object than that 

 which has been attributed to it. 



We have referred to the wide sweep of the rotating 

 extremity of the hop, but a still more remarkable 



